I have seen 7200RPM drives go for about this cheap, too - not sure if you're looking to upgrade right now, but keep your eye out for the faster drives going on sale at about $60-$70.
search CAG for 'PS3 HDD upgrade' (or something along those lines) I belive Shrike started the thread, but it has a couple options from a coouple different retailers. Hope that helps, good luck.
Getting a faster drive (7200RPM) can result in less battery life and more heat. I'm happy with mine. Also, be sure to stick that 80gb in a $10 enclosure (newegg) to have a nifty portable drive.