RE Audio 10" sub and small sealed Bassworx box. Box is a little big for the sub. $50. Langley. Specs on sub here:
10"
Electrical Q Value -Qes: 0.39
Mechanical Q Value -Qms: 4.37
Total Speaker Q Value -Qts: 0.36
Free Air Resonance -Fs: 21.5 Hz
Equivalent Compliance -Vas: 75.6 liters
One-Way, Linear Excursion -Xmax: 12 mm
Efficiency -SPL 1W/1m: 84.7 dB SPL
Effective Piston Area -Sd: 322 cm^2
DC Resistance -Re: 3.2 ohm
Nominal Impedance -Znom: Dual 4 ohm
Thermal Power Handling -Pe: 175 W
Force Factor -Bl: 15.4
http://reaudio.com/specs.html#sp_rex
REX series 10".