To estimate a maximum purchase price for the coin in question, we will consider several factors:

1. Current Condition: The coin has a condition rating of 75 (VF), indicating that it is in relatively good shape, although not among the highest qualities.

2. Auction History:
- The coin has been auctioned 5 times in the past, of which it has sold 4 times. This suggests there is consistent interest in the coin.
- The average hammer price in previous auctions is 200 euros, indicating that, in general, buyers are willing to pay significantly higher prices than the starting price.

3. Previous Auction Prices:
- In the December 2020 auction, the coin sold for 500 euros with a condition of 95.
- In April 2022, it sold for 240 euros with a condition of 85.
- In October 2020, it sold for 40 euros with a condition of 70.
- In the 2024 auctions, the hammer prices were much lower, which could indicate a decrease in interest or in the quality of the coins auctioned.

4. Starting Price and Estimates:
- The current starting price is 25 euros, which is quite low compared to the average hammer price of 200 euros.
- The average starting price in previous auctions is 82 euros, suggesting that the current starting price is below the average.

Based on these factors, an estimated maximum purchase price could be in the range of 150 to 250 euros, considering that the coin's condition is 75 and that the interest in it seems to be moderate. A price of 200 euros could be a reasonable target, given that it is the average hammer price in previous auctions. However, if there is strong competition in the auction, it could reach up to 250 euros.