Newegg via eBay offers the Western Digital 4TB My Book USB 3.0 External Hard Drive, model no. WDBFJK0040HBK-NESN, for $109.99. Check out via PayPal and apply coupon code "CMADNESS20" to drop the price to $89.99. With free shipping, that's $10 under yesterday's refurb mention (this one's new) and the lowest total price we've seen for this drive in any condition. (It's the best deal we could find today by $39.) It features local and cloud backup and up to 5Gb/s data transfer speeds.

Note: This coupon can only be used one time per account.