build your own. Not that hard. Go to home depot, buy the wood, have them make the cuts for you, take it home, glue and screw then borrow a jigsaw from a friend/neighbor/relative and cut the subwoofer hole. Viola you are done. Way cheaper and higher quality than pre-built junk places. Never EVER buy a prefab in your life ever again if you have any respect for your subwoofers.
Free box plans, I'd go with the 2@35hz
#2 and
#3 OR the 2.5@32hz box. Those would get you slamming properly.
*OFFICIAL* Free Ported Box Plans (56k NO!!) - Dodge SRT Forum
This is one of the members that had no idea how to build a box and attempted to do with with that exact 2.5 cubic feet at 32hz design.