Based on the provided data, we can observe that the coin in question had a starting price in the current auction of 18 euros, with a conservation grade of 30 (BC+). Additionally, it has been auctioned in the past on several occasions, with varying starting and final prices.

The average starting price of this coin in previous auctions has been 32.6 euros, while the average final price has been 63.88 euros. The coin has been sold in 8 out of the 10 previous auctions.

Analyzing the previous prices of this coin, we can see that it has had a wide price range, from 15 euros to 90 euros, with estimates ranging from 25 euros to 150 euros. The conservation grade of the coin has been assessed on different occasions, with values ranging from 30 to 80.

Given that the coin has sold in the majority of previous auctions and has had final prices higher than the current starting price, we could estimate a maximum purchase price in the range of 70 to 90 euros, considering the conservation grade and historical final prices. However, it is important to note that the final price will depend on the demand in the current auction and other factors that may influence buyers' decisions.