Are you willing to go the DIY route? I think a Adire DPL12 in a 152 liter sealed enclosure would be outstanding. A Q of .577, - 3db at 30 hz -6 db at 21 hz (anechoic). It could be built for a couple hundred.
Or you could contact someone like Brian at Rutledge Audio, or Kyle at Acoustic Visions to build it for you.