If PriceScope were to have Old Mine Cuts listed, you probably could pick up a stone with that grading for between $1200-$1600, depending on how well it's cut, and whether it's really an Old Mine Cut (cushion outline) or Old European Cut (round outline).
An Old Mine Cut would be more in the $1200-$1400 neighborhood, with an Old Euro being more in the $1400-1600 neighborhood.
That's on the internet. It probably would go for more out of a jewelry/antique store.