Hi Aaron, 

You've not told us much about the car - there are many many different versions of the Golf.

Estimating used car values is an inexact science at the best of times, and the market is abnormal right now with prices generally inflated. Regardless, the amount offered will vary considerably from dealer to dealer, too, so it's a very difficult thing to predict. Assuming yours isn't an R or GTI model, list prices seem to be from €12,000 to €19,000 depending on mileage and specification. As a trade-in, you should expect to be offered about €2,500 less than those of course as a dealer needs to make money on a trade-in when they sell it on.