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

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

2. Auction History:
- The average hammer price for similar coins has been 34.9 euros.
- In previous auctions, coins with a similar condition (95) have reached hammer prices of up to 125 euros (in 2015).
- The trend of hammer prices for coins in condition 95 has generally been positive, with several examples of sales in the range of 40 to 75 euros.

3. Starting Price and Estimated Price:
- The starting price is 20 euros, and the estimated price is 50 euros. This suggests that there are expectations for the coin to sell for a significantly higher price than its starting price.

4. Demand and Auction Frequency:
- The coin has been auctioned 102 times, with a 73.5% sell-through rate, indicating good demand.

Based on these factors, an estimated maximum purchase price could be in the range of 70 to 90 euros, considering that the condition is high and there is a price history that supports this estimate. However, given the auction context and potential competition, a maximum price of 90 euros could be reasonable to secure the purchase.