I agree that an AR15 would be a good choice for you. The group purchase at http://www.ar15.com sounds like a good deal. (www.ar-15.com is the web page for Wilson Combat)
It might be difficult to handle a AR-15 with no left hand as
some of the controls are kinda of small and meant to be done left handed. However there are speciality parts that would make them easier to manipulate from either hand.
