Based on the data provided, we can observe that the coin in question had a starting price in the current auction of 12 euros, with a conservation grade of 30 (BC+). Additionally, it has been auctioned eight times before, with an average starting price of 16.43 euros and an average closing price of 40.29 euros.

When analyzing the previous prices of this coin, we can see that it has had significant variations in its starting, estimated, and closing values over time. For example, in the auction on 2021-06-02, it was estimated at 70 euros and closed at 75 euros, while in the auction on 2022-05-31, it was estimated at 15 euros but closed at 75 euros.

Considering these data and the trend of previous prices, as well as the conservation grade of the coin, we could estimate a maximum purchase price around 60-65 euros. It is important to note that the final closing price may vary depending on the demand in the current auction and other factors that may influence buyers' decisions.