50xDVDr (about 235Gb, assuming no duds) = $25

750Gb hard drive = $150

I like to double up all my backups.

So $300 gets me 750Gb worth of doubled up hard-disk backup.

The same money gets me 1410Gb worth of doubled up DVDr backup.

Or DVDr is $1 per 4.3Gb backup.

Hard-disk is $1 per 2.5Gb backup.