Seagate 4 TB Backup Plus External USB 3.0 $139.99 Costco
I was at my local Costco & saw they had an instant rebate on the 4 TB Seagate Backup Plus external drive (Item 695080) $179.99 - $40.00 instant rebate = $139.99. According to the price slip, the rebate expires on 3/29/13.
The model # on the back says STCA4000600.
I do know there is the one at Newegg that expires today (3/23) under this thread:
However it looks like the model # is STCA4000100, so I'm not sure if there is a major difference between the two models.