I have decided that I'm going to build an AR-15. Seems like it is going to be more fun than just buying one (plus I can stretch out my budget rather than saving up). I'm going to pick up a lower this weekend. I have searching online for lower parts kits. It seems like the prices vary anywhere between about $40 and $100 (sometimes from the same company on the same website) without any explanation of what makes one better than the other. So, what do all you here recommend? What should I look for? What should I look out for?