What's the intended use? Long Range, Battle Rifle (short to med), bench rest? The intended use would lend itself to suggestions for additions.

Out of the box though, check the bolt carrier group, replace the extractor springs with a more liable set or at least buy the upgrade kit for when, not if, springs start to fail. Check the gas key staking, make sure that's good and solid. If not and if you're in the Denver area, I'm sure KellyTTE would be happy to help correct that issue.

Consider a new stock, flip down BUIS, optic type depending on intended use, LaRue or Badger rings/mounts for said optic if needed. A sling and bi-pod (if needed).
Oh and most importantly.. ammo.. lots and lots of ammo.

As for other .308 options. There are several that are in the high end range, e.g. well above your stated budget but their quality speaks for itself. That would be the LaRue OSR and the LWRC R.E.P.R.. If you're dead set on the AR platform, the DPMS or RRA is what you'll be able to get for that price range. Both require a but of tuning and initial love.