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

1. Coin Condition: The coin has a condition of 85 (ebc-), which indicates that it is in fairly good shape, but not the best possible condition.

2. Previous Auction Prices: By observing the hammer prices of coins with similar conditions, we can see that prices have varied. For example, in previous auctions, coins with conditions of 85 and 90 have reached hammer prices ranging from 14 to 220 euros, depending on demand and other factors.

3. Average Hammer Price: The average hammer price for this coin is 41.15 euros, which gives us a good reference for what buyers are willing to pay.

4. Starting Price and Estimated Prices: The starting price is 20 euros, and the average starting price is 25.53 euros. This suggests that the market is willing to accept a higher starting price, but it also indicates that there is a limit to what buyers are willing to pay.

5. Recent Trends: In the most recent auctions, hammer prices have shown a trend of increasing, especially for coins in good condition.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 60-80 euros. This range considers the good condition of the coin, market interest, and previous hammer prices. However, it is important to remember that the final price may vary depending on competition in the auction and specific demand at that time.