If I had the money just sitting around? I would probably go as high as $2,150. That puts you in Noveske/Knight's SR15 territory.
For that kind of money though I am expecting:
1. MOA or better accuracy and midlength barrel
2. Barrel life of at least 20,000 rounds under heavy training use, while maintaining the MOA or better accuracy for at least 10,000 of those rounds
3. Integrated midlength rail system with uninterrupted, free-floating top rail solid enough for sight mounting
4. Integrated folding sights front and rear (maybe option for fixed front)
5. Adjustable gas system
6. Quality aftermarket stock and controls
7. Quality trigger that is stone-cold reliable
8. Top-quality parts throughout
9. Muzzle-brake/QD suppressor adapter
However, I think in most cases you could get 95% of the quality at around $1,500 or less. Like 1911s and everything else, that last 5% gets costly.