We found this fairly good deal on a 400GB Seagate hard drive over at Outpost.com. The drive is $109 for 400GB, and ships free, which makes this around 27 cents a gigabyte. Mount this up on a cheap external enclosure and you've got yourself a great backup/music/porn solution.
SEAGATE 400GB PATA ST3400632A-RK. [Outpost]