B&H Photo-Video offers the Western Digital Elements 1.5TB USB 2.0 External Hard Drive, model no. WDBAAU0015HBK-NESN, for $69.49 with free shipping ($0.05/GB). That's the lowest total price we could find by $11 excluding the price below, although we saw this item for $7 less in March (since expired). This PC-ready drive can be reformatted for use with Macs.

Of note, Amazon has this hard drive for $69.99 with free shipping.