I considered the same a few months ago, and found some used ones on eBay. My concern was the material that was used to fill the butterfly shaft holes, and whether it could work its way loose. If that little bit of JB Weld or whatever was used fell into the cylinder, it could cost you an engine. I figured it wasn't worth the $100 savings to take the risk and bought the Steeda's through AM.
2007 GT Premium, Redfire. CAI. Bama Tune. CMDP's. Pype-Bombs. 3.73's. SR 62mm TB. Remote trunk mod. 20% tint.
2010 Xterra Off Road. (The tow rig)
2008 Commander. Hemi. (wife won't let me touch it)