I just picked up a copy at GameStop on Tuesday for $25 so I can clean up the rest of the achievements.
Granted, it was the last copy they had.
Also, apparently the game only sold around 300,000 copies when it was out, so there aren't as huge a number to come by as some other, more popular titles. Supply and demand generally dictate price...
In these fora and in real life, I've had it explained to me that the only possible reason that I use proper grammar and an above-average vocabulary when I post/speak is because I want to make other people feel stupid.
Thanks for bringing this to my attention.