Just saw this on Firearms Blog, looks pretty interesting. Do not fire the weapon while its folded though. When its folded theres no buffer spring to send the BCG back. $179 doesnt sound bad either to try it out.
http://www.thefirearmblog.com/blog/2012/05/03/law-tactical-ar-15-folding-stock-adapter/
http://www.lawtactical.com/ar-folding-stock.html#25



