Based on the provided data, we can observe that the coin in question has had an average auction closing price of 65.94 euros in previous auctions. Additionally, the current condition of the coin is 80 (MBC+).

Considering that the coin's condition is quite good and the average auction closing price in previous auctions has been 65.94 euros, we could estimate a maximum purchase price around 70-75 euros. Since the coin will be auctioned soon, the closing price may be slightly higher than this range, but as a conservative estimate, we could consider a maximum purchase price of 75 euros.