Based on the provided data, we can observe that the coin in question has had a starting price in previous auctions ranging from 18 to 60 euros, with estimated prices ranging from 30 to 100 euros. The average auction closing price has been 43 euros.

Considering that the coin's condition is 75 (VF), and taking into account the previous prices of similar auctions as well as the average closing price, we could estimate a maximum purchase price around 80-90 euros.

It is important to note that the final auction price will depend on the demand at that specific moment, so it is advisable to monitor its evolution to adjust the offer accordingly.

Based on the provided data, the coin to be auctioned has a starting price of 15 euros and a conservation grade of 30 (BC+). In the past, this coin has been auctioned three times, sold once, and remained unsold on the other two occasions. The average starting price in previous auctions was 35.67 euros, while the average final price was 15 euros.

Additionally, two previous prices of this coin in past auctions are provided:

1. In the auction on September 17, 2020, the coin had a starting price of 12 euros, an estimated price of 20 euros, and a conservation grade of 30. The final price is not indicated.
2. In the auction on May 31, 2022, the coin had a starting price of 80 euros, an estimated price of 100 euros, and a conservation grade of 70. The final price is not indicated.

Given that the starting price of the coin in this auction is 15 euros and considering the previous prices and conservation grade of the coin, as well as the fact that it was sold in one of the previous auctions, we could estimate a maximum purchase price around 100 euros. However, please note that the final price will depend on the demand at the auction and other factors that may influence the decision of potential buyers.