WTB $$$$ AR15 complete upper for a starter/economical build $$$$

[Slugz]

My sons 10th birthday is in 1 week and he's completed building his lower on his own dime so for his birthday i want to give him a completed rifle. Im trying to be under $300 if possible. Specs aren't too important and neither is brand but i do know palmetto has some pretty decently equipped uppers with good twist rates and popular options like m4 feed ramps and staked gas keys for about that price new, so looking to find something like that used maybe from either palmetto or rock river or spikes, etc... Would prefer carbine to mid length gas simply because he's a 10 year old so id like to keep it smaller but im open to full rifle length as well. Ultimately, it has to just be complete and in good firing order, and look newish. So bcg/ch included and some form of sights installed (prefer plain iron sights with a carry handle but flip ups or whatever work too)

Let me know what you got!

Best way to reach me fast is by text at 9259171337. Must be local to the concord/pittsburg/Antioch area or willing to either meet nearby or ship at my expense. Thank you!