Sure, they're very useful. Pick up some 556's too while you're at it. You can have 1/2 of the 556 in a monostable configuration, and use the other half in a variable frequency astable configuration, connected to trigger the other half - or myriad other configurations.
But instead of simply purchasing random components, why not get an experimenter's kit?
I highly recommend this one: http://www.radioshack.com/sm-electronics-learning-lab--pi-2102913.html
Yes, it's $65 - but you can spend lots more than that on components, and wind up with just junk box filler. The "breadboard" is almost too nice to be in a beginner's kit; you'll be using it for years. Comes with a couple of manuals written by Forrest M. Mims III - who also designed the experimenter's board. He did a heck of a job. The manuals are at once informative and entertaining, and you can start building useful circuits right away.
I suggest you put the plasma generator off for a while; you might wind up with a new hairdo that you don't particularly care for.
As far as optics, are you looking for lenses or something else?
You might check out Edmund Scientific - they've been around for a long time. They occasionally run specials on "grab bag" lots of lenses and other items.
I personally own 4 of the Electronics Learning Labs that SgtWookie mentioned. I seem to buy one every time we're out of town and I get bored. There seems to almost always be a Radioshack around to pick one up. A great bang for the buck! (I just bought #4 the other day down here in MS at the in-laws for the holiday!)