Based on the provided data, 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 25 times, sold in 22 instances, and not sold in 3 instances.

The average starting price of previous auctions has been 17.9 euros, while the average final price has been 34.9 euros. Previous prices for this coin vary, with estimates ranging from 12 euros to 60 euros, and final prices ranging from 14 euros to 65 euros.

Given that the conservation grade of the coin is 80 (MBC+), and considering the previous final prices as well as the average final price, we could estimate a maximum purchase price around 40-45 euros for this coin in the current auction. It is important to note that the final price may vary depending on the demand at the auction and other factors that may influence buyers' decisions.