I have a 10" sub box for sale for $50 shipped (Continental US only). It was cut off from a Sound Off Audio double sub box for a 2nd Gen DC. For pics of the entire unit, check out Sound Off Audio's web site. I cut the passenger side sub box off as I only wanted the amp board and the driver's side box, which I mounted behind the passenger seat.
This box is for a single 10" sub, it has .75 cuft air space and has the 6" mounting depth option. It can fit behind the rear seat on either side after the plastic bin is removed. As you can see from the pics, I did not finish where it was cut. Should be pretty easy to knock off the edge and smooth it out, but I did not do that, cheaper for you that way .
Any other questions, let me know.