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 shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History: By looking at previous hammer prices for coins with similar conditions, we can see that:
- In past auctions, coins with a condition of 95 have reached hammer prices of up to 110 euros (as seen in the auction on 2018-03-08).
- The majority of hammer prices for conditions ranging from 85 to 95 have been in the range of 50 to 110 euros.

3. Starting Price and Average Hammer Price: The current starting price is 45 euros, and the average hammer price in the past has been approximately 44.72 euros. This suggests that the starting price is reasonable and that there is potential for a higher hammer price.

4. Sales Trends: The coin has been sold in 51 out of 61 auctions, indicating good demand and a history of successful sales.

Based on these factors, an estimated maximum purchase price could be in the range of 90 to 120 euros, considering that the condition is high and there are precedents for hammer prices in that range. However, since the starting price is 45 euros, it is likely that the hammer price will not significantly exceed the upper range of 120 euros unless there is intense competition in the auction.

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