I really want to get into the world of AR's but im having trouble deciding the best route to take? I'd like a 11.5"or 14" upper and I'd also like to get Magpul accesories like Miad grip and all the rest, so my question is would it be better to just buy one someone has already tricked out or should i build my own from the ground up? Will it cost me alot more than $2000 to build a nice looking CQB AR or do I buy a used one? Also how many rounds out of a used one would you recommend staying away from? 1000? 2000? I dont know like i said im a noob and would like to not spend too much more than $2000. Thanks for your time