I know JBL makes a wireless subwoofer. I have the wired subwoofer of theirs and it is great. I have it paired with a couple of Klipsch floor-standing speakers and powered by an Onkyo receiver. You can always use Apple's Airplay to wirelessly control your music throughout your home too, which is really nice.
2012 E92 M3 | MW | DCT | KW V3 | Edition Cosmetics | 19" MORR VS8.2 - Brushed w/ Tinted Clear | F1 Pinnacle 35%