Walmart offers the Schumacher 10/2 Fully Automatic/Manual Dual-Rate Car Battery Charger, model no. SE-520MA, for $49.99. Pad your order over $50 to bag free shipping. (Amazon charges the same.) That's the lowest total price we could find by $12. It features jumpers, two output voltages, overcharge protection, and charges a battery fully in three to five hours.