Lets go one step further.....how about a 4-10 or 4-12 speaker cabinet. As long as its wired series/parallel, which I would imagine it would be in an 8 ohm application, that with the 2-12's would be a very nice set up to say the least.
Price wise, I have seen several 2-12's listed for $100 and the 4-12's or 10's for $200 on ebay and Guitar Center. Guess its your call as to how bad you want it or how motivated the seller is to part with the cabinet. The bargains are there if your willing to wait and watch.
Hiding equipment from the misses.......it will come back to bite you on the butt. Just go out and buy her something shinny and sparkling, and it doesn't have to be diamonds. Never met a woman yet who didn't respond to that one. You might even get lucky in the deal.