Focal 8WM Utopia M Series 8" 4-ohm component woofer at Crutchfield
Goldwood Heavy Duty 12 in. Woofer 450-Watt 8 ohm Replacement Speaker GW-12PC-8 - The Home Depot
AIYIMA 8 Inch Subwoofer Speaker Woofer 4 8 Ohm 150W High Power Long Stroke Deep Bass Hifi Sound Loudspeaker DIY For Home Theater|Bookshelf Speakers| - AliExpress