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

1. Coin Condition: The coin has a condition of 75 (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 observing the hammer prices of coins with similar conditions (around 75), we can see that the hammer prices have varied. For example, in previous auctions, coins with a condition of 75 have reached hammer prices of up to 110 euros.

3. Average Hammer Price: The average hammer price for this coin is 97.71 euros, which can also serve as a reference.

4. Auction Trends: The coin has been auctioned 172 times, of which 142 have been sales. This indicates good demand and consistent interest in the coin.

5. Starting Price: The starting price is 50 euros, suggesting that the seller expects a reasonable price, but the final price could be significantly higher.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 120-130 euros. This is based on the analysis of previous hammer prices for coins of similar condition and the general interest in the coin.