Your best bet is to order one on line your probably waisting time on here. Just make sure it comes with complete bolt carrier group and charging handle. Most everyone on here including myself wont have a $300 upper. If we did we would probably build a cheap lower and then sell it as a complete rifle. Thats being honest. I just ordered one from Sota arms. There is also a gun show at Big Town this weekend in Mesquite. Good luck on the build with your son.