Based on the provided data, we can observe that the coin has had a starting price in the current auction of 18 euros and is in a conservation grade of 75 (MBC). Additionally, it has been auctioned in the past on several occasions, with varying starting and final prices.

The average starting price of the coin in previous auctions has been 32.25 euros, while the average final price has been 54.69 euros. The coin has been sold in 17 out of the 20 previous auctions.

Some previous prices of the coin have ranged between 10 and 230 euros, depending on factors such as conservation and demand at that time.

Given that the coin is in a conservation grade of 75 (MBC) and has had previous final prices that have exceeded the current starting price, we could estimate a maximum purchase price around 40-50 euros for this particular auction. However, please note that the final price may vary depending on demand and other factors at the time of the auction.