I have a 20" G5 iMac from when they first came out, and my power supply's dying on me. The local Mac Genius tells me they can't just sell me the individual part to replace myself. It already had the logic board replaced under a warranty extension program long ago, but apparently that was a one time thing and this time I'm not covered. Anyone know where I could get a power supply online for not too much $$? Cheapest one I've found online is 99 bucks, so far.