Buy via eBay offers the Seagate 3TB Expansion USB 3.0 External Hard Drive, model no. STBV3000100, for $89.99 with free shipping. That's $10 below last month's mention and the lowest total price we could find by $18.
Although the product description at Fry's advertises USB 3.0 connectivity, according to Western Digital, it only supports FireWire 400 / 800 and USB 2.0. It's formatted for Mac, but can be reformatted for Windows-based systems as well.