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

2. Previous Prices: By looking at previous auction prices for coins with a similar condition (85), we find that at the auction on 2022-12-14, a coin with the same condition was sold for a hammer price of 90 euros. This suggests that the market has valued coins in this state at a high range.

3. Starting Price and Average Hammer Price: The current starting price is 40 euros, and the average hammer price in the past has been 37.11 euros. However, given that the condition is good and there is interest in the coin (sold 30 times in the past), it is reasonable to expect that the hammer price will be above the average.

4. Auction Trends: The coin has been auctioned 30 times and has had a 100% sell-through rate, indicating strong demand. This may influence an increase in the hammer price.

5. Estimation Based on Previous Prices: Since the highest hammer price for a coin with a similar condition was 90 euros, and considering that the starting price is 40 euros, an estimated maximum purchase price could be in the range of 80 to 100 euros, depending on the competition in the auction.

Conclusion: Based on all these factors, an estimated maximum purchase price for the coin could be approximately 90 euros. This reflects both the condition of the coin and the price trends in previous auctions.