If there's a Fry's near you, the one near me (City of Industry) recently got a big stock in. You can also get one from Defender at http://www.videogamedeals.com
I'm thinking about getting this game, it is really worth the $50 asking price. I have never spent that much on a game, and just wanted to know if it's worth it.
If it is your first $50 game, no it isn't. It's good and all, but if you are unwilling to cough up $50 for any other game this one definitely doesn't deserve it.