Based on the provided data, we can observe that the coin in question had a starting price of 18 euros in this auction, with a conservation grade of 30 (BC+). Additionally, it has been auctioned in the past seven times, being sold in all of them. The average starting price in previous auctions has been 31 euros, while the average final price has been 68.14 euros.

When analyzing the previous prices of this coin, we can see that it has had a wide price range, with estimates ranging from 25 euros to 90 euros. The highest price reached in a previous auction was 120 euros.

Given that the coin has been sold in all previous auctions and considering the average final price of 68.14 euros, as well as the highest price reached of 120 euros, we could estimate a maximum purchase price for this coin around 130-140 euros, taking into account its conservation and the demand it has shown in previous auctions.