I found a dead computer at the top of our driveway (we share it with a motel apartment thing), and someone had obviously abandoned it. Not sure if it got left out in the rain, probably.... does care. Soooooo like any right-minded engineering student, I immediately grabbed it and scuttled back home to see what I could scavenge.
As well as 2 disc drives and a floppy drive (which will be dismantled later, A] for shits and gigs and B] for potential motors, linear actuators and other goodies), the PSU was still inside. While it is only rated for 300W which is not enough for a modern computer, that's more than enough for a desk power supply.
The unit provides supplies for GND, 3.3V, 5V and +-12V, as well as a standby 5V which is always on when its plugged in. There is also a wire allowing a switch to be added for turning it on and off without unplugging it. I decided to add an LED to indicate that it was turned on as well, just in case.
I have never been able to do electronics at home (apart from what runs on USB) due to the lack of a scope and a power supply, so this solves half the problem at least.