Steve, if it really is a 6 cylinder, it will be worth somewhere in the neighborhood of 8 to 10k, maybe a little more if it's in good condition, less if it's in bad shape.
Since it was only a "dress-up" item, the RS option was available on any Camaro regardless of engine however, RS cars bring more than standard cars, so that's a plus. Verify ALL the RS parts are still on the car! These can get very costly to replace.
Good luck and keep us posted.
Ed