Apparently with the release of the PS3 version of Mass Effect 2, retailers are having a problem keeping it in stock.
According to a tweet by Bioware they just cant seem to keep them in stock, which makes them happy but still in an effort to help gamers find this amazing game they set up a helpful thread on their forum. Please note this only affects people who want to get the retail copy, if you happen to want the digital copy (for the same price) you can always get that off the Playstation Network. If you do opt for the digital version keep in mind that its 12 gigs.
Mass Effect 2 (PS3) Is Rare According to Bioware,