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

1. Current Condition: The coin has a condition of 85 (ebc-), which indicates that it is in quite good shape. This generally translates to a higher value compared to coins with lower conditions.

2. Auction History:
- The average hammer price in previous auctions is 47.22 euros.
- In past auctions, hammer prices of up to 180 euros have been reached for coins with similar conditions (for example, 95).
- The last auction where a similar coin with a condition of 90 was sold reached a price of 55 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 25 euros, and the average starting price in previous auctions is 28.93 euros.

4. Sales Trends: The coin has been sold in 76% of the auctions it has participated in, indicating good demand.

Based on these factors, an estimated maximum purchase price could be in the range of 70 to 90 euros. This is based on the fact that the condition is good and there are precedents for higher hammer prices in the past. However, since the starting price is 25 euros, it is likely that the final price will not significantly exceed this range unless there is strong competition in the auction.

Therefore, a reasonable estimated maximum purchase price could be 80 euros.