Staples offers the Seagate 4TB Backup Plus USB 3.0 External Hard Drive, model no. STCA4000100, for $129.99. Coupon code "25147" drops it to $119.99. With free shipping, that's $0.03/GB and tied with yesterday's mention as the best price we've seen. (It's also a current price low by $40.) It features two backup scheduling options and social network sharing.
Note that in order to redeem the rebate, you'll need to activate the Total Defense software, which involves providing your credit card information. However, you can cancel the service at any time within the first year without any additional charges.