To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the current condition of the coin.

1. Current Condition: The coin has a condition of 75 (MBC), indicating that it is in quite good shape.

2. Previous Auction Prices: By looking at the auction prices of coins with similar conditions (around 75-80), we can see that auction prices have varied, but generally, coins in good condition tend to reach higher prices.

3. Recent Auction Prices:
- In 2022, a coin with a condition of 80 was auctioned for 65 euros.
- In 2023, a coin with a condition of 80 was auctioned for 50 euros.
- In 2020, coins with a condition of 80 were auctioned for 55 euros.

4. Price Trends: The average auction price for this coin is 33.34 euros, but considering that the current condition is 75, which is better than many of the coins that have been auctioned in the past, we can expect the auction price to be above average.

5. Estimation: Given that the condition is good and considering the previous auction prices, an estimated maximum purchase price could be between 50 and 70 euros. This is based on the fact that coins in similar conditions have reached auction prices in that range.

Therefore, an estimated maximum purchase price for this coin could be 65 euros.