All4Cellular offers the XPAL PowerSkin Extended Battery Case for HTC Amaze 4G Smartphone, model no. AP1513RUBT, for $12.95. Coupon code "A4C10" cuts it to $11.65. With free shipping, that's the lowest total price we could find by a buck. This silicone skin case features a built-in 1500mAh battery, LED battery status lights, and USB charging cable. Deal ends January 13.