Based on the provided data, we can see that the coin in question had an opening price in this auction of 18 euros, with a conservation grade of 70 (MBC-). Additionally, it has been auctioned in the past four times, with an average starting price of 13.75 euros and an average closing price of 44.75 euros.

In the previous auctions, we can observe that the coin has had starting and estimated prices ranging from 1 to 30 euros, with closing prices reaching up to 110 euros on one occasion. The conservation grade of the coin in the previous auctions was 80 on one occasion and not specified in the other two.

Given that the coin is in a conservation grade of 70 (MBC-), and considering the previous closing prices, we could estimate a maximum purchase price in this auction around 60-70 euros. 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.