270 WSM ammo can easily be loaded to shoot at 3400 fps or thereabouts and it isn't that hard to get mil-dot values out to 1000 meters for something like that. You can get ballpark mil-dot distances simply by doing retrocalculations with a decent ballistics program.
That's about right. It really boils down to how much you want to spend on the scope. I am looking to build a 1000 meter rifle later this year. I am thinking about buying a used .300 Win Mag long action Remington 700, put a new barrel with a compensator on it and a tactical stock. Then the real expense is the scope. The total package will be over $1000, but it isn't exactly a varmint rifle, it is closer to a poor man's M24.