Based on the data provided, we can observe that the coin in question has had a starting price in the current auction of 18 euros and is in a conservation grade of 80 (MBC+). Additionally, it has been auctioned in the past on several occasions, with closing prices ranging between 5 and 55 euros.

The average starting price of previous auctions has been 14.88 euros, while the average closing price has been 24.15 euros. The coin has been sold in 13 out of the 15 previous auctions.

Considering the previous prices of the coin and its current conservation grade, as well as the fact that it has sold in the majority of previous auctions, we could estimate a maximum purchase price around 35-40 euros for this coin in the current auction. This estimation is based on the price history and the demand it has shown in previous auctions.