I actually found a pretty decent NSR clone, but the only bad thing is that it's made in china.
I'm not sure how much of a budget you are looking for. I used mine to make my budget build as cheap as possible ($415 before I got the brace/sights/foliage green stuff). I inspected the barrel nut before building it of course. The provided set screws were pretty good quality and had no risk of stripping.
The only thing that sucked about them was the free keymod rail attachments. They were just heavy and the finish sucked.
The rail actually had decent finish, laser etched T marks, rails are in spec, keymod slots were in spec, and it included shims. It seems like Rifle Supply has pretty decent quality control. The only pain was perfectly lining up the rail with my upper. I had a tiny bit of OCD there. There was a slight trick to tightening down the barrel nut screws.
The rail/barrel nut is very solid. But this is only a 7" rail, there is no telling if a longer length will have wobble.
Not bad for $53 shipped, but if I knew about the Matrix hand guards, I would have purchased one instead.
7" NSR Clone by RifleSupply
The 10" version is here.
10" NSR Clone by RifleSupply
Another nice option are the rails Primary Arms put out. They are made by Seekins.
Primary Arms Seekins Rail 9" Model
Also Parallax Tactical is a great company to deal with.
Check their
facebook
They sometimes have blems for sale for only $110
9" model here.