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

1. Current Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in relatively good shape. This suggests that its value should be in the upper range of previous auctions.

2. Previous Auction Prices: By looking at previous auction prices for coins with a similar condition (around 80), we can see that they have reached hammer prices of up to 90 euros in recent auctions. For example, at the auction on February 16, 2023, a coin with a condition of 80 was sold for 90 euros.

3. Average Hammer Price: The average hammer price for this coin is 74.63 euros, which also provides a reference point.

4. Auction Trends: The coin has been auctioned 47 times, of which 41 have been sold. This indicates good demand and consistent interest in the coin.

5. Starting Price and Average Starting Price: The starting price is 40 euros, and the average starting price is 45.45 euros. This suggests that the hammer price could be significantly higher than the starting price.

Based on these factors, an estimated maximum purchase price could be in the range of 90 to 100 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate. Therefore, a reasonable maximum purchase price could be 100 euros.