Or less. Or more. To be fair, I have seen pretty nice GT's sell for as little as $1000, and pretty ratty ones for as much as $2000. And nice ones for $15,000 (OK, it was REALLY nice!) and barely drivable ones for as little as $200. It really depends on where you live, and the exact circumstances. Some folks (like a certain Jim M.) might believe that every GT is worth at least $5000, and good ones at least $10,000, but he is the eternal optimist. And salesman incarnate.
Timing is everything. The other Calgary Opeler (who will go nameless to protect the guilty) bought his GT from his girlfriend's uncle for $1. Yes, one dollar. Canadian. Which is about 71 cents on a recent good day. The uncle was the original owner, it had a very good body and fresh paint (minor rust inside the rockers and the usual suspect places), ran well and was in "lower Class 3 or upper Class 4" (more about that in a second). It should have sold for at least $3000 Canadian (which usually means the same amount in Yankee bucks, given the market place up here), but the uncle wanted it to go to a good home. And John has given it a VERY good home, and is about to bestow it with a stroked 2.2, big valve head, high compression Chevy pistons, a ported manifold, and 5-speed Getrag. He thought it was only fair that he spend what he should have paid for the car in the first place. Of course, it will now be worth $4500, since you NEVER get more that half what you put into a car. And especially an Opel.
And as for the "Classes", Charles Goin has compiled an excellent appraisal guide on the Opel Association of North America site, at:
http://clubs.hemmings.com/clubsites/oana/value.html
Have a look. Based on your too-brief description, it might go for as little as $500, and as much as $3500. But that largely depends on the body. Rust-free cars are on the upper end, rust buckets on the lower.
HTH
