mmm 1tb usb 3 seagate hdd for $129, I saw seagate 2tb usb 3 for $99 at JBhifi yesterday and 3tb for $129
Yeah that's usb-powered 2.5" 1TB vs power-packed 3.5" 2TB/3TB.
The physically smaller drive that doesn't require extra power cables is usually more expensive for obvious reasons.
Much better to get a portable Buffalo 1TB drive from somewhere like CA for $149. Much more reliable than the piece-of-crap Seagates on the market that will flake out on you in no time.