AR-10 denotes Armilite rifles and no others its not a term covering all rifles of the ar pattern.
2700$ is a good budget, if I had that budget to play with, I would be looking at a Larue or a LMT rifle myself. I like the LMT due to is modularity, they offer 4 rounds in their rifle I would consider better for 1000yard targets than the standard 308 win. The 7mm-08, 260 rem, 6.5 creedmore and 243 win.
That said nothing wrong with the GAP for 2700$ but I would be happier with an MWS or an OBR etc. A 16" barrel will get you to 1k with the right bullet.
As far as LMT goes the website list the factory price but if you shop around 2400$ is avarage.
.308 Modular Weapon System, 16" Chrome Lined - Firearms
With Larue the price is the price
Rifles | LaRue Tactical