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

1. Current Condition: The coin has a condition 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 similar conditions (80 and 85), we can see that auction prices have varied. For example:
- In 2021, a coin with a condition of 85 was auctioned for 140 euros.
- In 2023, coins with a condition of 80 have been auctioned with starting prices of 60 and 75 euros, but they did not sell.

3. Starting Price and Average Hammer Price: The current starting price is 60 euros, and the average hammer price in the past has been approximately 34.92 euros. However, since the condition of this coin is better than many that have been auctioned previously, we can expect the hammer price to be higher.

4. Auction Trends: The coin has been auctioned 21 times in the past, of which 13 have sold. This indicates a consistent interest in the coin, which may increase its value.

5. Condition-Based Estimation: Given that the condition is 80, and considering that in the past similar coins have sold in a range of 25 to 140 euros, we can estimate that the hammer price could be in a higher range due to the good condition.

Taking all these factors into account, an estimated maximum purchase price for this coin could be in the range of 80 to 100 euros. This is based on the condition, previous hammer prices, and the interest in the coin.