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 rating of 80 (MBC+), 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 similar conditions (80 and 75), we can see that they have reached auction prices of up to 120 euros (in the auction on October 17, 2022) and 100 euros (in the auction on March 18, 2021).

3. Starting Price and Average Hammer Price: The current starting price is 60 euros, and the average hammer price in the past has been 71.29 euros. This suggests that the hammer price could be in a similar or higher range than the starting price.

4. Sales Trends: The coin has been auctioned 22 times, of which 18 have been successful sales. This indicates a steady demand, which may influence a higher hammer price.

5. Previous Estimates: The estimated price in previous auctions has varied, but it has reached up to 110 euros in a prior auction.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 100 to 130 euros. This is based on the current condition, previous hammer prices, and the trend of successful sales. However, it is important to note that the final price may vary depending on competition in the auction and other market factors.