u/ImpossibleSport23

I recently just found a subwoofer on the curb that works. No info written on it other than it's 8 ohm. Are there any single channel amps out there under 40$? it's a 6 inch sub and a mystery brand so I don't want to put any money into it. I figure it would add some bass to my otherwise OEM 99 4runner. Don't know much about audio and wattage. I assume the after market head unit I have doesn't have enough output to wire up the sub directly. Everything I've looked at on Amazon is multi channel and Bluetooth or has like a 20 watt output. Any recommendations?