$800-$1200 IF you can find an original. There are tons of originals in the U.S. but most are not on the market. The $400-$500 repros confuse people and the novices will shy away from a real one assuming you are trying to rip them off.
Two things to look for are flat screws on the turret knobs, although new repro scopes have correct domed screws. Other thing to look for is a green krinkle finish scope with a serial number like 434342 or 424243. This was done by one of the manufacturers as a dead giveaway.
The biggest problem is that most of the people who are experts and have a real sniper, AREN'T and DON'T.
Original deactivated snipers will have a serial number under the wood line of the stock for their original scope.
Other than that, I have pretty much no "off the top of my head" info on them. In short, if you see a green scope with flat turret screws and a serial number of 424243 you should walk away.
I own firearms not to fight against my government, but to ensure I will not have to.