To estimate a maximum purchase price for the coin that is going to be auctioned, we can consider several factors:

1. Coin Condition: The coin in question 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. Auction History: By looking at previous hammer prices for coins with a similar condition (80), we can see that the hammer prices have varied. For example:
- In 2020, a coin with a condition of 80 was auctioned for 50 euros.
- In 2022, another coin with the same condition was auctioned for 70 euros.
- In 2023, a coin with a condition of 80 was auctioned for 75 euros.

3. Average Hammer Price: The average hammer price for this coin is 52.24 euros, which can also serve as a reference.

4. Starting Price: The starting price of the auction is 50 euros, indicating that the seller expects a minimum price of 50 euros.

5. Recent Trends: In the most recent auctions, hammer prices for coins with a condition of 80 have been in the range of 55 to 75 euros.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 70 to 80 euros, considering that the condition is good and there is a trend of increasing hammer prices for similar coins.

Therefore, an estimated maximum purchase price could be 75 euros.