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

1. Coin Condition: The coin has a condition rating of 80 (MS+), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Previous Prices: By looking at previous auction prices for coins with a similar condition (80), we can see that the hammer price has varied. For example, in past auctions, coins with a condition of 80 have reached hammer prices of up to 45 euros.

3. Average Hammer Price: The average hammer price for this coin is 49.04 euros, which is also a good indicator of the expected value.

4. Recent Trends: The coin has been auctioned 135 times, of which 124 have been sold. This indicates good demand and consistent interest in the coin.

5. Starting Price: The starting price is 25 euros, suggesting that the auctioneer expects considerable interest in the coin.

Based on these factors, an estimated maximum purchase price could be around 60-70 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate. However, it is important to keep in mind that the final price may vary depending on competition in the auction and the interest of other buyers.