Trade in on an Audi A4 1.8T cabriolet in 'good' condition with those miles is $21k if you have all the regular toys, and not the quattro, according to
www.kbb.com. In my experience, if the dealer is not making his mark up on the sale, he's doing it on the trade in. Trade in value is also dependent on where you 'deal'. Where I live, you see an Audi about every three weeks. Part of your problem on this trade in and any future trade in will be the mileage and anyone who buys your Audi, no matter how pristine it is, is going to use the fact that you have excess miles and that the warranty period is about to expire!