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

1. Condition: The coin has a condition rating of 80 (MS+), indicating that it is in quite good shape. This generally translates to a higher price compared to coins in lower condition.

2. Auction History:
- In the past, this coin has been auctioned 4 times, of which it has sold 2 times. This suggests that there is moderate interest in the coin.
- Previous hammer prices are relevant. For example, in 2016 it sold for 110 euros, establishing a high benchmark. In 2022, it was auctioned with a starting price of 50 euros and an estimated price of 75 euros, indicating that the market is willing to pay more for coins in better condition.

3. Starting Price and Average Prices:
- The current starting price is 75 euros, and the average hammer price in the past has been 71 euros. This suggests that the starting price is reasonable and could attract bidders.

4. Market Trends: Given that the coin has a history of hammer prices that vary, and considering that the condition is good, it is reasonable to expect that the hammer price could be above the starting price.

Taking all these factors into account, an estimated maximum purchase price could be between 100 and 120 euros, given the auction history and the condition of the coin. This would allow a competitive buyer in the auction, considering that interest in the coin may vary.