treo ssp

Its a Treo Engineering SSP 12" Subwoofer in new condition. Whats it worth?

I have two 12" treo ssp and I have kept them even without a vehicle for the past two years. I really wanna put them in my new car but I need a box. I'm not good with math but I can build a deck with my eyes closed. Can anyone lend a hand..maybe give me a blueprint. Lol I can get you any of the...