iEGrow via Amazon offers Prime members its iEGrow 2-Bay Smart Li-ion LCD Battery Charger for $18.99. Coupon code "GYEN89B2" drops it to $11.99. Plus, Prime members bag free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $6.27.) That's $15 off list and the lowest total price we could find. It features a voltage detector and recharges 3.7-volt lithium-ion batteries. Deal ends November 30.