To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Current Condition: The coin has a condition rating of 75 (MBC), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Previous Prices: By looking at past auction prices, we can see that there is considerable variability. For example, in previous auctions, coins with similar conditions have reached hammer prices ranging from 20 to 500 euros, depending on demand and other factors.

3. Average Hammer Price: The average hammer price for this coin is 85 euros, which can serve as a good reference point.

4. Starting Price: The current starting price is 25 euros, suggesting that there is considerable room for the hammer price to be higher.

5. Sales Trends: The coin has been auctioned 42 times, of which 36 have been sold, indicating a good sales rate and sustained interest in this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 100 to 150 euros, considering that the condition is good and that interest in the coin appears to be solid. However, it is important to keep in mind that the final price will depend on the competition in the auction and the demand at that specific moment.