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 of high quality. This generally affects the price, as coins in better condition tend to reach higher prices.

2. Auction History: By observing previous hammer prices for coins with similar conditions, we can see that:
- Coins with a condition of 75 have reached hammer prices of up to 630 euros in recent auctions.
- The majority of coins with conditions ranging from 70 to 80 have had hammer prices ranging between 400 and 600 euros.

3. Average Hammer Price: The average hammer price for this particular coin is 576.84 euros, which provides a good reference point.

4. Starting Price: The starting price is 25 euros, suggesting that there is considerable room for price increase during the auction.

5. Recent Trends: In the most recent auctions, hammer prices have shown a trend of being in the range of 600 to 800 euros for similar conditions.

Based on these factors, an estimated maximum purchase price for the coin could be in the range of 600 to 800 euros. This is based on the historical hammer prices for coins of similar condition and the observed average hammer price. However, since the condition is not the highest, it is wise not to exceed 800 euros in the bid.