I need a box for a Fi BL 12 sub woofer   I would rather buy one unless it exceeds around $150.  I would like it to be ported but I'm not sure if it will fit in my truck.  I have a 2000 ford ranger XLT and I want to keep one back seat  so it can't be to big.  Any suggestions on pre-made boxes or if it's truly worth it, where can I learn how to build a perftect box for the BL 12.