Based on the provided data, the coin will be auctioned with a starting price of 18 euros and is in a conservation grade of 75 (MBC). In the past, this coin has been auctioned twice, both times it was sold, with an average starting price of 16.5 euros and an average closing price of 32.5 euros.

Additionally, we have information about a previous auction of the same coin that took place on November 19, 2020, where the starting price was 15 euros, the estimated price was 25 euros, and the closing price was 25 euros, with a conservation grade of 70.

Given that the conservation grade of the coin to be auctioned is slightly higher than the conservation grade of the previous auction (75 compared to 70), and considering the starting price of 18 euros, we could estimate a maximum purchase price around 30-35 euros, considering the previous average closing price of 32.5 euros and the improvement in the conservation of the coin.