Do I have to get a bench power supply to work on electronics on a breadboard? I know I can power an LED from a Raspberry Pi, but once you get more stuff on the board you need external power. I don't want to spend money on a power supply yet. Can I use a battery? These would be small projects for learning. I also saw a kit with the that will connect to the wall for cheap, but that looks dangerous.
Edit: The kits I've seen use the LM317, but again, it's a screw down block for wires from the wall (I think). I'm not sure that's good.