Let's see...
a Creative Labs Audigy 2NX external soundcard. Does 5.1 surround and has optical I/O. $75 shipped.
Rane AC22 2way stereo/3way mono active crossover. Very solid unit that takes one 19" rack space. Currently wired for 120VAC, but probably could be modd'ed for 12V. $80 shipped.
Ported box for two 12's, tuned to 28Hz. Originally built for two e12a's, so it's around 1.5cF per sub. Carpeted gray, slot port painted black. If you're interested, talk to me about shipping - I'd like to get around $90 shipped for it.