Sold through Ebay by Newegg. I'm not sure what drive is inside the enclosure. This is the cheapest 4TB drive I've seen. Also some low prices on the smaller drives at the bottom of the TechBargains link.
http://www.techbargains.com/samsung-d3-station-deals?source=newsletter&subsource=1892
eBay (via Newegg) has the Samsung D3 Station STSHX-D401TDB 4TB USB 3.0 External Hard Drive for a low $119.99 Free Shipping. Tax in CA, IN, NJ, TN. This drive sells for $140+ elsewhere and quite possibly the lowest price we've ever seen for a 4TB hard drive.
Features fast data transfer speeds with the USB 3.0 interface by connecting to a USB 3.0 port. USB 3.0 is also backwards compatible with USB 2.0 (although you will have USB 2.0 speeds).