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

1. Coin Condition: The coin has a condition rating of 95 (EBC+), indicating that it is in very good condition. This generally translates to a higher price compared to coins with lower condition ratings.

2. Auction History: By observing previous hammer prices for coins with a similar condition (95), we can see that they have reached hammer prices of up to 130 euros in the past (as in the auction on October 18, 2018).

3. Average Hammer Price: The average hammer price for this coin is 65.1 euros, which gives us an idea of what buyers are willing to pay on average.

4. Starting Price: The starting price is 50 euros, which can influence the final price, as buyers often consider the starting price as a reference point.

5. Sales Trends: The coin has been auctioned 40 times, of which it has sold 30 times. This indicates good demand, which can drive up the hammer price.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 100 to 130 euros, given that this price has been reached in previous auctions for coins of similar condition. However, a more conservative price could be around 90 to 100 euros, considering the average hammer price and the starting price.

Therefore, a reasonable estimated maximum purchase price could be 100 euros.