Hard drive prices
are really great right now. 500 and 750 GB drives are both sitting at just below $0.17/gigabyte and 1000 GB drives are at $0.22/gig--and that's the average price. If you need storage, now is the time.
I picked up a 1000 GB drive for backups at $205--under $0.21/gig. I plan on backing my entire RAID-5 array with it.