For hard drives I generally just head to ZipZoomFly.com -- their prices are generally as good as if not a little better than NewEgg, and they seem to usually have a slightly better selection. It's one or the other, regardless.
Although it's annoying from the MB/MBP perspective that they don't yet have a seperate section for 2.5" SATA drives--they're all mixed in with the 3.5" drives, so it's a pain to do a quick comparison.
They sell the Seagate 100GB 7200RPM for $180, and the 100GB 5400RPM for $130. You're not likely to do a whole lot better. Hitachi drives are $170 and $140 for the same specs in the Travelstar line (though the 7200RPM isn't in stock).