Hifonics Brutus BRZ12D4 - $65 Amazon.com: Hifonics Brutus BRZ12D4 12-Inch 4-Ohm DVC Subwoofer: Car Electronics
Belva Sub Box 1SV12B - $55 Belva 1SV12B Single 12" Vented MDF Enclosure - Sonic Electronix
Decent quality box, it has poly lines walls, which i like.