5TB Seagate Backup Plus External 2.5" Portable Hard Drive HDD USB 3.0 Red Price increased from $169 to $179, however, 5TB is still available for $135.20 from the following links (thanks pixxelpusher)
2TB = $31.63 per tb
4TB = $25.8 per tb
5TB = $27.04 per tb
The 4TB is best value per tb, however, 2tb ones are shuckable into laptops as they are 9mm. 5TB is red and goes faster ;)
Even cheaper with Swap eBay Gift Cards!