I recently got the newest edition of Brownells AR15 catalog and got to thinking I wanted to change out my upper receiver. I currently have the A2 upper but want the flat top since I am planning purchasing a aimpoint and do not want it to ride so high on the carry handle. I also plan on doing a basic remodel of the upper with Flip up front and rear sights, piston set up, new possibly DDF or YHM and a VFG. Something my wife brought is that would it be cheaper to sell the current upper and buy a new one how I want it or just upgrade from what I have now. i have looked to trade just for a normal flat top but have been unable to come across one. Has anyone else done this before if not throw your opinions out there I take everything into consideration. Thanks.