How much are you looking to spend and how much boot space are you looking to keep?
I have a Rockford box with 2 x 12" subs installed and an alpine V12 amp that is all going on eBay at the weekend - might be of interest to you if you want to go thumpa thumpa...
I also have a JL box with a JL 10" sub. Not as low or rumbly as the 12's, but superbly punchy. This will be going on eBay also.