This might be a little off topic... but converting an old computer PSU to a benchtop power supply is very easy to do, and also really cheap. You won't get as tight a voltage regulation as you would on a real one, but the one I recently converted is pretty decent as the voltage only varies within a few percent of the target.
I turned a 480 W power supply into a benchtop, and so far, am very happy with the results.