Based on the provided data, 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 80 (MBC+). Additionally, it has been auctioned in the past on several occasions, with varying starting and estimated prices.

The average starting price of previous auctions has been 27.13 euros, while the average final price has been 24 euros. The coin has been sold in 7 out of the 10 previous auctions.

Considering the coin's previous prices and its current conservation grade, as well as the fact that it has sold in the majority of previous auctions, we could estimate a maximum purchase price around 35-40 euros. This estimation is based on the current starting price of 15 euros and taking into account previous final and estimated prices.

It is important to note that the final auction price may vary depending on the demand at that specific moment, so it is advisable to monitor the auction's progress to adjust the offer accordingly.