Based on the data provided, we can observe that the coin in question has had a starting price in this auction of 12 euros, with a conservation grade of 20 (BC-). Additionally, it has been auctioned eight times in the past, with an average starting price of 44 euros and an average closing price of 57.13 euros.

When analyzing the previous prices of this coin, we can see that it has had closing values ranging between 17 and 100 euros in previous auctions. The conservation grade of the coin has varied in each auction, but overall it has remained within an acceptable range.

Given that the starting price in this auction is 12 euros and considering the previous closing prices, as well as the conservation grade of the coin, we could estimate a maximum purchase price around 70-80 euros. It is important to note that this is just an estimate and the final price could vary depending on the demand at the auction.