*snaps fingers* That could be it, thanks Squilliam
Due to the larger development costs of PS360 games compared to PS2/GC/Xbox, the length of many games has been cut, in order to try to make a profit. However, that then means that PS360 games could suffer more from being resold, hence lowering profits, hence why they need to be $10 more.
Hmm, a bit convoluted, but maybe the 2nd hand market is more damaging to the PS360 than to any other console?