I'm pretty new to all of the information with Semi Auto rifles, but I've been looking around at some rifles with the gas piston system. I have found that they can be pretty expensive to just buy one straight out, so I was thinking about buying the parts to build one and put it together myself. I figured I could buy the parts to put together an Ar style rifle with some sort of gas piston upper, but I only want to do that if it would save me a pretty good amount of money...Obviously. So I'm wondering if anyone out there builds their own rifles often and knows if it is actually worth it to build the rifle yourself? Also, around how much money would it cost to build a good reliable AR style rifle with a gas piston upper as apposed to buying that type of rifle at a gun shop? (When looking at just purchasing the gun I was looking at a bushmaster for around 1,500 dollars. But I would love to build it for cheaper if possible) HELP PLEASE!