Based on the data provided, we can observe that the coin in question has had a starting price in the current auction of 15 euros, with a conservation grade of 30 (BC+). Additionally, it has been auctioned in the past on several occasions, with closing prices ranging between 15 and 35 euros.

The average starting price of previous auctions has been 28.46 euros, while the average closing price has been 40.17 euros. The coin has been sold in 92.3% of previous auctions.

Considering these data, as well as the previous prices of the coin in past auctions, and taking into account that the current conservation grade is 30 (BC+), we could estimate a maximum purchase price around 40 euros. It is important to note that this is just an estimate and the final price could vary depending on the demand in the current auction.