A couple of months ago I purchased an 87 GN with Astroroof with 4,700 miles for $19,700. Like someone else said, there are very few of these cars that haven't been molested in one way or another. You can still replace almost every part on these cars, but you can never roll back the miles! I think $20,000 is a pretty realistic figure for a loaded, unmolested 87 GN with less than 7,500 miles. In 1987 only 2,560 Regals (all models) were built with the factory Astroroof. I haven't been able to find the figure on how many of those Regals were GN's, but whatever the number there weren't very many of them.