If you can find one on Ebay for cheaper, it will still be built like a tank.
XPlay ran a console endurace test day before yesterday, in which they subjected all three consoles to torture tests in order to see which one was the toughest. They first dropped a 25 pound weight on all three consoles. It demolished the PS2, but the other two were in perfect condition. Then they took a sledgehammer and smashed both the XBox and GCN with it. Both were fine. Finally, they dropped both consoles from a 25-foot roof onto cement. The XBox broke almost in half. The GCN survived the fall and still played games perfectly afterwards.
One way or another, you buy a GCN and it will outlive you. If you can find one on Ebay for 20 bucks, you won't get a POS. There's no such thing as a POS Gamecube.