Based on the data provided, we can observe that the coin in question has had an average auction closing price of 309.85 euros in previous auctions. Additionally, the conservation of this coin has remained constant at 85 (ebc-).

Considering that the starting price in the upcoming auction is 325 euros and the estimated average closing price has been 309.85 euros, we can assume that the closing price will likely be in a range close to this value.

Given that the coin has had a good sales history and its conservation remains constant, we could estimate a maximum purchase price around 320-330 euros, considering the trend of previous prices and the fact that the coin has successfully sold in previous auctions in this price range.