Ya just get one new from Burger Tuning about $110 shipped. Not sure you'll find a used one shipped for much savings unless its local to you.
I have a 2006 mustang GT as well. It's my aggressive car while the 335i is more refined. Good luck with your mods!
2007 335i AW, Premium, Cold Weather. Mods: M-sport st.wheel, DCI, COBB ST1 aggressive tune, VMR V718s, Eibach B12 Pro-Kit, Euro headlights w/luxe90v6
2012 x5d AW, Premium, Sport, Sound, 3rd Row