newegg offers the Seagate Backup Plus 4TB USB 3.0 Portable Hard Drive, model no. STCB4000102, for $159.99. Coupon code "AFNJ2697" cuts it to $149.99. With free shipping, that's the lowest total price we could find by $19. This drive is compatible with Windows and Mac and features a 4-foot USB 3.0 cable and pre-loaded Time Machine software. Coupon expires October 16.