Amazon offers Prime members the Boss Armor 1,500-watt Mosfet Car Radio Amplifier, model no. AR1500M, for $44.99 with free shipping. (Non-members can spend $35 to bag free shipping; otherwise, it adds $5.99.) That's the lowest total price we could find by $8. It features high and low level inputs, variable low pass crossover, and remote subwoofer control.