Fry's Electronics offers the Hitachi Deskstar 7K4000 4TB Serial ATA 6Gb/s Internal 3.5" Hard Drive, model no. 0S03355, for $249.99 with free shipping ($0.06/GB.) That's the least expensive 4TB internal hard drive we've seen. (It's a current price low for this model by $26.) Sales tax is added where applicable. It runs at 7200 rpm and features a 64MB cache.