I spent about 4 months building my first AR15. That was my introduction to the platform, never having owned an AR pattern rifle before I built mine. It came with long hours of reading, research, and plain ole bargain hunting. I would wait for bargains on parts to show up and I slowly assembled the components I needed. $30 here. $50 there. Browsing the swapshops on various forums for cheap components. Keeping an eye out on various deal alert threads on various forums. Including the optic but not counting tools I built my rifle for $470. The lower in this picture I got for free from posting a review online about the 80% arms Easy Jig which I used to machine my lower. If you take that into account that bring the price to $440 including optic for this rifle. The one questionable part I used would be the cheap gas block. Other than that everything else is MilSpec from good quality vendors. Things like 7075 buffer tubes instead of the cheaper 6061 buffer tubes can be easy to miss without a lot of research. It's been quite reliable over it's first 1000 rounds. I think as long as you get quality milspec parts it's pretty hard to screw up and build a bad AR15.