Based on the provided data, we can observe that the coin in question has had an average auction closing price of 27.34 euros in previous auctions. Additionally, the current condition of the coin is graded at 95 (EBC+), indicating that it is in quite good condition.

Considering that the starting price in the upcoming auction is 15 euros and the estimated closing price is 25 euros, we could estimate a maximum purchase price around 30-35 euros, taking into account the historical prices and the condition of the coin.

It is important to note that the final closing price may vary depending on the demand at the auction and other factors that may influence buyers' decisions.