A cheap SCSI drive option are SCA server drives with a 50 pin adapter board. I've got a few of the Seagate Savvio 2.5" drives in old Macs, the advantage of the 2.5" being they're much quieter than typical server drives. I think I paid $7 each for the drives and around $3 for the adapter. 72GB but I'm only using 2GB partitions on most.
