I bought my first, a S&W M&P15A. I have since built 5. I have had no issues with my home built ARs. It usually isn't cheaper, but you get what you want in a way you can afford it. Buy fast or buy slow. If you are patient, you can find almost everything on sale over a month or two.
Shopping at places like Palmetto State Armory, Joeboboutfitters, DSG Arms, JSE, PK Firearms, Rainier Arms, The Citizen Armory, Aim Surplus and Primary Arms can save you a lot of money. One of them always has a sale going.
The first home built will be more expensive, because you have to buy a few tools; Armorer's wrench, vise, upper vise blocks, punches, etc. Not terribly expensive, but it will add to the cost of the first build.
If you go pure economy and or sales, you can build a nice AR for under $800 plus tools cost. It might take you 4 months.
Walkalong's link above is a heck of a deal. If I was shopping for an AR, I would order that.