PowerPC :: G5 IMac - Unexpectedly Shutdown

It's a G5 20" 2.0ghz machine and is 15 months old approx. He was running something or other, nothing very taxing, when the computer unexpectedly shut down. He restarted it and within a few mins it shutdown again. He restarted it again and used it fine for a couple of hours, shut it down and went to bed. Came to it the next day and nothing. No noise, no lights, nothing. He dropped it off at a local authorised dealer and they thought it was either going to be the power supply (�100 to fix) or the main board (�600 to fix). Sure enough he got the call and it's the logic board thats gone. He doesnt have applecare unfortunately but decided to try his luck and contact apple anyway. Needless to say, they weren't in the least interested and told him he'd either have to foot the bill or toss the machine in the bin. �600 to fix one of these is appauling and more than the machine itself is worth but the options are limited. Has anyone else experienced anything like this and if so are there places to get the machines fixed cheaper? I know this goes to show that it's a good idea to stump up the extra cash initially for applecare but �1200 (the price when new) seems pretty bad for 15 months computing and has really put me off recommending iMacs to anyone else. The days when I can construct my own computer with my own components and run OS X on it, and repair it myself cant come soon enough if this is how it's going.