Try looking at the clearance section at Best buy (These are usualy near the counter, sometimes behind).
The ones near me are switching out old hard drives with new ones, I got my brother a 320 GB one for $60 bucks. Granted, this was around Christmas, but the manager I talk to there says they're going to be doing it for a bit.
From what I understand, the newer models (Western Digital is the brand) have more restrictions on them, so it won't hurt you.