On mine, the large board is held in place by the LCD header, 2 screws for the rotary encoder, half a dozen plastic tabs above and below the board, the 4 pushbutton switches, and the 4 plastic screw columns that fit in corresponding notches on the board. The main stress point is the power jack and the hole in the case looks like it will prevent much motion. I think it's a clever package.

At the time of purchase my version was recommended by Amazon and now it's delisted. I get the impression the copy cats get ahold of pending patents and mass produce under many names. I stopped buying from Amazon for the most part because of the marketing bias. I don't buy much outside North America either. That being said I've found electronics to be very expensive if you want quality gear and getting out of the junk tier takes some good spending.

 

At the time of purchase my version was recommended by Amazon and now it's delisted.

There's a lot of junk being sold on Amazon. You can often buy the same thing on Ali Express for significantly less. In fact, some of the pictures and descriptions used on Amazon are exactly the same as what's used on Ali Express.

This FNIRSI PRO is selling for more than twice what I paid on Ali Express (though AE prices are around $40 now):

That being said I've found electronics to be very expensive if you want quality gear and getting out of the junk tier takes some good spending.

I have a DSO138, DSO150, and DSO FNIRSI PRO and they're pretty much toys for me. My preferred scopes are Tektronix from the 70's and 80's. I bought them for dimes, or less, on the dollar of the original selling price. My "bench" scope is a 7704A 200MHz scope with 4 channels and 2 time bases. When I'm not at my bench, I'm most likely to use a SC503 (now that my 466 needs repair).

 

If I remember correctly, it is the 3rd iteration of that scope. The first did not have a case but you could buy a plexiglass sort of case for it. Then the small screen with integral case and now the larger screen model. I do like its portability and does work well albeit a bit fragile as the case is simply cosmetic and does not provide a great deal of protection. Not sure of the big screen models but the prior ones were kits, but the 2nd model had the option to buy it already built.

 

Goodness - for $70 you can probably find a reasonably good 2 channel analog tektronix scope on ebay. For about 3x this you can probably get a brand new 2 channel rigol or siglent.

 

approximately <2x the price - same price per channel.

Tektronix Model 2225 50MHz 200MSa/s 2 Channel Analog Oscilloscope | eBay $180
Tektronix TDS320 100 MHz, Dual Channel, Digital Oscilloscope | eBay $140 - and digital
TEKTRONIX 2430A 2CH OSCILLOSCOPE | eBay $120
Tektronix 2211 Digital storage Oscilloscope | eBay - $160
TEKTRONIX 2212 60MHZ 2CH DIGITIZING OSCILLOSCOPE | eBay -$110

And I only spent 5 minutes looking.

 

for $70 you can probably find a reasonably good 2 channel analog tektronix scope on ebay.

Used equipment prices are outrageously high now; has been for a number of years now.
$135 and $160 for parts scopes.

When prices were more reasonable, I bought a 2GS/s HP scope for $30. Got a 76xx scope with plugins for the same price. Both had no shipping because the seller was a 30-40 miles away and I bought a lot of surplus equipment and parts from them, so I was usually out there at least once a month. They no longer offer local pickup and I stopped buying from them.

 

approximately <2x the price - same price per channel.

Tektronix Model 2225 50MHz 200MSa/s 2 Channel Analog Oscilloscope | eBay $180
Tektronix TDS320 100 MHz, Dual Channel, Digital Oscilloscope | eBay $140 - and digital
TEKTRONIX 2430A 2CH OSCILLOSCOPE | eBay $120
Tektronix 2211 Digital storage Oscilloscope | eBay - $160
TEKTRONIX 2212 60MHZ 2CH DIGITIZING OSCILLOSCOPE | eBay -$110

And I only spent 5 minutes looking.

None of those scopes meet your original price point.

 

Brand new scopes - To be clear, I think these 'scopes' are pretty crappy, but they are certainly a big step up from what you have... for a little more than 3x. They're brand new, and I assume have some of the capability.
1000Z Mixed Signal Oscilloscopes | RIGOL (rigolna.com)
SDS1000DL+ Series Digital Storage Oscilloscopes - Siglent (siglentna.com)

I personally think this is the best entry level scope on the market, but it's a bit more pricy to have name-brand, high quality gear.
InfiniiVision 1000 X‑Series Oscilloscopes | Keysight

To be

None of those scopes meet your original price point.

3 of them did... $140, shipped, is 2x $70. A couple more are more expensive, but were also $20k scopes a few short years ago, and are a bargain today.

 

I'm in the the market for a new or old scope. I'm willing to spend north of $300 for something that will last me and meet mathematical expectation as I continue to learn. I've noticed many users opt for older scopes where the trace is superimposed onto a grid painted on the glass instead of new scopes that are digital. I looked at a few presented here and they look like relics, any special reason for using older equipment? Of course newer isn't always better and the features are more than sufficient?

 

any special reason for using older equipment?

It depends on when you started learning electronics. I became a fan of Tektronix gear while I was in community college. We only had one Tek 7704 mainframe in the electronics lab and it was popular. It has dozens of plug-ins.

In addition to vertical amplifiers (7A*) and time bases (7B*) plugins, there were frequency counter (7D15), digital scope (7D20), logic analyzers (7D01, 7D02), DMM (7D13), curve tracer (7CT1N), spectrum analyzers (7L*), time domain reflectometer (7S12), 1GHz sampling scope (7S14). The 76xx mainframes were 100MHz, while 77xx, 78xxx, and 71xx went from 200MHz-1GHz.
EDIT: corrected scope families.

I'm still looking for reasonably priced curve tracers, spectrum analyzers. I'd like a TDR, but I'll probably build my own because the plugins I don't have are expensive.

I've all but given up on a 7CT1N. They usually go for $600+. For that price, I could buy a high power standalone Tek curve tracer. I bought two standalone curve tracers for about $50 each. One of them was a recent purchase and the seller priced it reasonably as a buy it now and I bought it. Others are currently expecting $200-400.

7603 with a 7D20 was nice. The 7603 had the largest screen. It's my favorite setup for the 7D20, but I'll put in a 7704A too.


I also like the TM5xx mainframes:

This one has a scope and a pulse generator.

In a TM504, I typically install a scope, function generator, and power supply.

 

I'm in the the market for a new or old scope. I'm willing to spend north of $300 for something that will last me and meet mathematical expectation as I continue to learn. I've noticed many users opt for older scopes where the trace is superimposed onto a grid painted on the glass instead of new scopes that are digital. I looked at a few presented here and they look like relics, any special reason for using older equipment? Of course newer isn't always better and the features are more than sufficient?

The older CRT scopes will generally provide you professional level gear with a little more bandwidth for a comparable price. Stick with Tektronix 2000 series as these are high quality, name brand scopes, and aren't too old. They were overengineered and generally last long past their useful life. The older 7000, 500 and 400 series scopes are still really good, but I've found more issues with them at their age.

The newer LCD scopes have a lot of functionality that is useful for things like serial decode, smaller physical size, segmented memory, sometimes a function generator, and sometimes a digital sampling section. You get more stuff that can be used for todays electronics... but it's often lower bandwidth.

I'd personally buy one of each if you can afford it - they both have their benefits.

 

There are Several reasons for picking an older analog scope, the first is performance per price: A used scope that works will usually offer better performance and accuracy than a new scope of similar price. And those older scopes that are most common sold a lot more of them because they were good. In addition, there is usually more information on using the older scopes, more accessories available, and mostly no custom ICs that are no longer available. The one downside is that the older scopes usually have a lot of hours on the CRT and if that fails a replacement may be expensive. But scope CRT s do last a long time.
Also, an older scope is more likely to be repairable if that is ever required. Super compact construction is really hard to repair.
AND, analog scopes do have better resolution than digital scopes.

 

Which 3 brands would each of you recommend? It will be a while until I buy one so I'll start researching the top companies.

 

Top tier: keysight and tektronix
2nd tier: rhode&schwarz and teledyne lecroy
3rd tier: siglent, rigol, gw instek, and maybe a couple others, but these are the most popular.

For hobbiest use, 3rd tier is fine and generally well equipped. A lot of people are happy with these options.