You are in a heap of trouble now. An AR is like the infamous Mrs. Marcos and her shoes! Thousands of pairs!!!
Your AR has so many options and if you are not careful like a little pac-man on the billfold. But man what fun you can have doing it!
It just depends on what you are going to do with it. Also what kind of optics did it come with. You can put on a two piece quad rail that will hold lights, vertical grips, lasers. Oh where does it stop.
We here on the FTF will be more than glad to assist and help you spend your money!! LOL
Seriously let us know what you are thinking about for it and we can give you our advise and in put on selection options, quality of products and etc.