I have a pair of 2.25 cu ft 12" sub cabs that I got from the diysoundgroup site that it turns out I can't use due to a change in the layout of our media room. These are nice CNC cut MDF flat packs that I glued up. They're sized for the Dayton RSS315, but my NHT 1259's also fit.
Looking to recoup maybe $50 for the pair, which I think makes for a pretty good deal for someone.
link to the flat packs
http://www.diysoundgroup.com/flat-packs-1/subwoofer-flatpacks-2/2-sub-flat-pack.html