SO I am in the (slow) process of building a NY compliant rifle, but I was curious about some of the parts and kits out there. For a lower parts kit, do all kits pretty much contain the same parts? I have seen them as low a $35 with a trigger group (not really sure what that is yet) and as high as $250. What's the difference? And what about bolt carrier groups? Huge difference and does finish make a huge difference? Beside the upper and lower receivers, BCG, lower parts kit and barrel, what other items do I need? I'm going the route of the exile machine co stock so hopefully will be within NY ridiculous laws... I don't care if I have parts from different manufacturers, as long as the rifle is reliable, any help would be greatly appreciated, thanks in advance all.