Newegg offers the Toshiba 500GB Canvio Slim II 500GB Portable USB 3.0 External Hard Drive for Mac in Silver, model no. HDTD205XSMDA, for $39.99. Coupon code "NAFBF14A" drops it to $37.99. With free shipping, that's the lowest total price we could find by $13. It's Apple Time Machine compatible. Deal ends today at 11 pm ET.