I have a JBL GT-BassPro12 for sale. I had it in my Tahoe for about 6 months but I sold it. It has the amp built in and is ready to go. I also have the bass knob that goes along with it. $200
JBL GT-BassPro12 Ported powered subwoofer with 12" sub and 150-watt amp at Crutchfield.com
JBL GT-BassPro12 Ported powered subwoofer with 12" sub and 150-watt amp at Crutchfield.com