Walmart discounts a selection of automotive and garage items, with prices starting at $1.32. Opt for in-store pickup to avoid shipping fees, which start at $4.97, or receive free shipping on orders of $50 or more. A couple of best bets, both with pickup:
Nutrend via Newegg offers the Schumacher 410-watt Power Inverter, model no. PID-410, for $24.99 with free shipping. That's $5 under our mention from May and the lowest total price we could find by $18. It features two 120-volt AC outlets, a digital display, and built-in cooling fan.