You can adapt a PC AT-style PSU, I did this years ago on my first A2000.
The A2000 pin outs are here:
http://pinouts.ru/Power/amiga2000power_pinout.shtml The AT PSU pinouts are here:
http://pinouts.ws/at-power-supply-pinout.html Just pair the matching wires from the AT pin outs to the A2000 pin outs.
The AT power supply doesnt provide a "tick" signal so you will need to set J300 (Check its J300 on your board, this may vary by board revision!) on the A2000 motherboard to the other postion when using the AT PSU.
Check, check and double check your wiring before powering it up!!
