My take for what it's worth. If you will be using this rifle to defend your life in a "war like" situation then the premium money buys you extreme dependability. Redundancies that have been learned in combat situations, things like proper staking of bolts in critical areas. If on the other hand you want a serious plinker that could go to battle then you decide how many of those mission critical areas you can forgo. Chrome lined chamber and barrel are an example, if you will be able to clean and store the weapon properly I don't see it as a big deal.
The fastest place to spend money is on the accessories. If you absolutely want to hang a light from the forend get a railed forend right from the getgo cause there isn't much use for a spare in the closet. Trigger upgrades are the same way, get it done at the factory.
Or... build it yourself one piece or component at a time. Get a book, get a bit of trigger time on a buddy's AR, then sit down at the computer with a credit card and enjoy. It takes a minimum of specialty tools depending on how much you want to do piece by piece. There are even instructional videos out there.
If you are pretty happy with the other rifles you have, then you will be pretty happy with most any AR. If you are never happy with an out of the box rifle, then build your own. If you aren't a tinkerer but plan on wearing out barrels, and competing with others in fast paced compititions the find a Colt or other premium build gun.