The big question is just what do you need a breadboard for?
For me, I was looking at testing out a variety of circuit designs before I went to the expense of actually making the real thing. I found that a "trainer" was pretty much what I needed. It is a couple of breadboards but has variable AC and DC power supplies, plus a wave generator, some switches, etc.
So, for some of us a simple battery or single fixed power supply may be enough with a breadboard, but for others that will be quite inadequate. That's why they make most without the power supplies.
For me, I was looking at testing out a variety of circuit designs before I went to the expense of actually making the real thing. I found that a "trainer" was pretty much what I needed. It is a couple of breadboards but has variable AC and DC power supplies, plus a wave generator, some switches, etc.
So, for some of us a simple battery or single fixed power supply may be enough with a breadboard, but for others that will be quite inadequate. That's why they make most without the power supplies.