I agree if you can find the space for 15 that'd be sick, the sub would be around 270 shipped and the amp around 265. That'd leave enough in your budget to buy some mdf and make a box, plus buy some good 4awg on eBay. If you don't want to do a blow through then make a custom console with a 12" that 1 twelve would do a lot of damage in a single cab if put in the right airspace
agreed now get to building im waiting