BC Master via Amazon offers the BC Master 18-watt USB Wall Charger for $9.99. Coupon code "RTGGF9FV" drops it to $4. Plus Prime members bag free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $6.14.) That's $16 off list and the lowest total price we could find. It includes a 3.3-foot microUSB cable.