Based on the data provided, we can observe that the coin had an opening price in this auction of 12 euros, with a conservation grade of 70 (MBC-). Additionally, it has been auctioned in the past four times, with an average starting price of 25.75 euros and an average closing price of 43.75 euros.

We also have information on previous prices of this coin in past auctions:

1. In the auction on November 19, 2020, the coin had an opening price of 9 euros, an estimated price of 15 euros, and a closing price of 15 euros, with a conservation grade of 30.
2. In the auction on May 28, 2014, the coin had an opening price of 12 euros, an estimated price of 20 euros, and a closing price of 20 euros.
3. In the auction on October 17, 2022, the coin had an opening price of 70 euros, an estimated price of 100 euros, and a closing price of 70 euros, with a conservation grade of 80.

Given that the coin is in a conservation grade of 70 (MBC-), and considering the previous prices and the closing trend, we could estimate a maximum purchase price of around 60-65 euros for this particular auction. It is important to consider that the final price may vary depending on the demand at the time of the auction and other external factors.