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 85 (ebc-), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for similar coins in condition 85 has been 55 euros (at the auction on 2020-12-15) and 30 euros (at the auction on 2020-02-13).
- In other auctions, the hammer price has varied, but the range seems to be between 30 and 70 euros for similar conditions.

3. Starting Price and Average Hammer Price:
- The current starting price is 40 euros, and the average hammer price in the past has been 44.63 euros. This suggests that the hammer price could be in a similar or slightly higher range.

4. Sales Trends: The coin has been auctioned 36 times, of which 27 have been successful sales. This indicates a steady demand, which may influence a higher hammer price.

5. Previous Prices: Previous hammer prices for coins with similar conditions have reached up to 110 euros in the case of a condition of 95, but for conditions of 85, the prices have been lower.

Based on these factors, an estimated maximum purchase price for this coin could be between 60 and 70 euros, considering that the condition is good and there is a price history that supports this estimate. Therefore, a reasonable maximum purchase price could be 70 euros.