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 of 80 (MBC+), indicating that it is in relatively good shape. This suggests that its value could be in the upper range of previous auctions.

2. Previous Prices: By observing the hammer prices of coins with similar conditions (around 80-90), we can see that the hammer prices have varied. For example:
- In 2022, a coin with a condition of 90 was auctioned for 35 euros.
- In 2023, a coin with a condition of 85 was auctioned for 28 euros.
- In 2024, a coin with a condition of 80 was auctioned for 30 euros.

3. Price Trends: The average hammer price for this coin is 65.8 euros, indicating that, in general, buyers are willing to pay more than the average starting price (43.41 euros).

4. Analysis of Previous Auctions: The coin has been auctioned 28 times, with a 78.57% sell-through rate (22 out of 28). This suggests that there is consistent interest in this coin, which may increase its value at auction.

5. Estimation Based on Condition and Previous Prices: Given that the condition is 80 and considering the hammer prices of coins with similar conditions, an estimated maximum purchase price could be between 50 and 80 euros, taking into account that the average hammer price is 65.8 euros.

Conclusion: An estimated maximum purchase price for this coin could be approximately 75 euros. This is based on the condition, previous hammer prices, and the general market trend.