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

1. Current Condition: The coin has a condition of 75 (MBC), which indicates that it is in an acceptable state, but not among the best qualities.

2. Historical Prices: By observing the hammer prices of coins with similar conditions (75-80), we can see that the hammer prices have varied, but generally have remained in a range of 450 to 600 euros in recent auctions.

3. Average Hammer Price: The average hammer price for this coin is 576.84 euros, which gives us a good reference for what buyers are willing to pay.

4. Recent Trends: In the most recent auctions, the hammer prices for coins with similar conditions have been in the range of 600 to 800 euros, suggesting that there is growing demand.

5. Starting Price: The starting price is 25 euros, which is quite low compared to previous hammer prices.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 600-700 euros, as this price reflects both the current condition and recent market trends. However, it is important to remember that the final price may vary depending on the competition in the auction and the interest of collectors at that time.