If you don't mind size, buy a standard 3.5" Internal SATA drive and put it in a USB or SATA drive enclosure. The drive enclosures generally run for 10 to 20 dollars US which seems to be the most cost effective. I Also priced out some smaller 2.5" Terabyte drives and external drive enclosures, but found they were similarly priced as just buying a pre-built 2.5" external drive.. I did all my price checks on Newegg.com