eBay is pretty much your best bet for the 50-pin SCSI drives that the 7300 uses. They come in 1, 2, 4, 9 and 18GB sizes -- be wary of "adapted" drives, though as I've had trouble with them in the past... try to get a true 50-pin drive, and not a 68-pin drive that's been "adapted" to 50-pins.