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

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

2. Price History: By looking at previous auction prices for coins with similar conditions, we can see that the average hammer price for coins with a condition of 80 is approximately 95 euros, based on past auctions.

3. Average Hammer Price: The average hammer price for this particular coin is 76.12 euros, which is also an important indicator.

4. Auction Trends: The coin has been auctioned 56 times, of which it has sold 48 times. This suggests good demand and sustained interest in the coin.

5. Starting Price: The starting price is 40 euros, which is reasonable and may attract bidders.

Taking all these factors into account, an estimated maximum purchase price could be around 95-110 euros, as this price reflects both the condition of the coin and the price history from previous auctions.

Therefore, a reasonable maximum purchase price could be 100 euros.