"Bare" usually means it has no cables (or a CD - which is usually of no importance to a Mac owner anyway) and doesn't come in a pretty box. Since the new Macs all have the cabling you need in them already and most of us toss the pretty boxes and can't use the CDs, "bare" is just ducky.
That is one honking drive!! Granted - prices have dropped incredibly and it is possible to do even better on GB/dollar basis:
http://shop1.outpost.com/product/4795199 for instance - $300GB for a mere $80.
But if you want to absolutely max out your internal storage, then the bigger the better. Do make sure that whatever you get will be recognized by either the Mac or the enclosure. I've seen some enclosures which will only take up to 300GB for instance. Not sure whether there are any restrictions with the newer Macs; if there are, I haven't heard about them.