The real question is how many unmodified GNs still exist....I'd guess maybe 2
You be surprised how many 100% stock 1987's are still out there. Even though you can make a 100% stock appearing one run 11's with just tires and race gas, they chose to keep the stock fuel pump that craps out at a 13.9 - dumb.
GN prices were artificially kept down for years, because when a low mileage car sold for over $20K, 25 more came out of the woodwork. It has only been in the last 4 years that this stopped happening, and the prices on stock, low mileage cars has gone way up.