Amazon has the Seagate Expansion 3TB USB 3.0 External Hard Drive (STAY3000102) for $130 with free shipping. Select Amazon.com as merchant (in sidebar); temporarily out of stock but can still be purchased. Includes power adapter and measures 1.54" (H) x 4.96" (W) x 8.17" (L).
how fast this one can transfer data?
as fast as a 7200 rpm seagate over USB3.
why do these have external power? I thought one of the main features of USB 3 was increased power to be able to handle hungry drives?