asking $10 to cover shipping.

It's a radio shack converter. Converts 120V AC to 12V DC. I used it for awhile in high school to use my automotive subwoofer as a powered sub for my home stereo system.

How many amps (or is it watts)?

The back says 60Hz, 40 Watts Max.

Basically this has a plug for a standard outlet, and then a positive and negative screw on the back, where you attack the wires for the output.

I don't remember what I paid for it 10 years ago, I just know it will cost me about $10 for a box and shipping.

I always held onto it thinking I might use it, but I haven't used it in 10 years.

You used an automotive subwoofer on a 40 watt peak supply??! aren't you an electrical guy? lol