B&H Photo-Video offers the HGST 4TB Deskstar Coolspin 3.5" SATA Internal Hard Drive, model no. 0S03359, for $154.95 with free shipping. That's the lowest total price we could find by $10, although it was $3 less in January. It spins at 5400rpm and features a media transfer rate of up to 1366MB/s.
There's a less expensive way, and then there's the way that works for you. The two may not be the same.