This site offers a reconditioned A1000 PSU for $29:
http://www.oldsoftware.com/Amiga.htmlHowever, if it's an old fashioned linear PSU it should be quite easy to diagnose and fix. The form factor makes me think it's a SMPS though?
Switched PSUs typically suffer from a few common modes of failure. Without trying to teach you to suck eggs, I've found this guide to be very useful in the past:-
http://www.repairfaq.org/sam/smpsfaq.htmI have to admit though, the last SMPS I tried to diagnose I ended up simply replacing.
If you do make any progress I'm sure your experiences (positive or negative) would be useful to others.