Based on the data provided, we can observe that the coin in question has 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 the coin in previous auctions has been 38.45 euros, while the average final price has been 50 euros. The coin has been sold in 9 out of the 11 previous auctions.

When analyzing the previous prices of the coin, we can see that it has had starting and final values ranging from 15 to 90 euros, with estimated prices ranging from 25 to 200 euros. The conservation of the coin has mostly been good, with conservation grades ranging between 70 and 80.

Given that the coin has been 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 around 60-70 euros, considering the conservation grade of the coin and historical final prices. However, keep in mind that the final price will depend on the demand in the current auction and other potential interested buyers.