I'll have to answer better when I get back to the house ,I'm ripping and running doing errands right now , but honestly I think it really depends on what your doing with it. Because the whole "buy the best you can afford" thing.... I really feel now days is a over rated saying for most people. Manufacturing and quality has just gotten to the point where you can get the quality that used to cost and arm and a leg for , not pocket change, but not something that's gonna gut punch you and your wallet.$1900 is a good chunk of change for a off the shelf ar but without me knowing what your gonna be using it for , I can't really give a good thought process on it. I mean if you've shot that model and just really really like it then I can't blame you get it ! But if your just wanting to shoot a dozen coyotes a year feed it green tips 80% of the time not have it in the worst condition ever actually clean it once every blue moon and plink with it like most guys ...heck you can do all that with a $700 PSA. Again not hating if you just like the more expensive option I'm just a lot more frugal and there's just a lot of good options out there for just average use .
As far as building one, trust me if you can change your oil or assemble a cabinet or something you and build a half decent AR-15. AR-10 are a bit tricker though but AR-15's are basically like Legos when it comes to average use. Alot of people try to make it seem way more complicated then it is ( like reloading) for some reason. And you don't need a don't of tools either . I have a $200 armors kit from real avid with a lot of fancy tools ....and I don't use 70% of them . Honestly it's usually just the action rod,the wrench and the torque wrench .
Personally though I'd just see if you could go to one of those stores with a range and just shoot and handle a bunch . NOT EVERY AR IS THE SAME ! But yeah shoot a few buy one you really like and use if for a few months . See what you really want to change what you don't like what you do like and remember it. Now when you build one you actually have an idea of what YOU want in YOUR build.