Based on the provided data, the coin will be auctioned with a starting price of 12 euros and is in a conservation grade of 30 (BC+). In the past, this coin has been auctioned twice, both times it was sold, with an average starting price of 15 euros and an average closing price of 25 euros.

Additionally, we have detailed information from a previous auction held on April 28, 2022, where the coin was auctioned with a starting price of 18 euros, estimated at 30 euros, and finally closed at 20 euros. On that occasion, the conservation grade of the coin was 70 (FDC).

Given that the conservation grade of the coin to be auctioned now is lower than the conservation grade of the previous auction (30 instead of 70), it is likely that the closing price will be lower than the 20 euros obtained in the previous auction. However, considering that the average closing price in the past was 25 euros, we could estimate a maximum purchase price around 22-23 euros for this coin in the current auction.