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 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 this coin has been 17.29 euros.
- In previous auctions, coins with a similar condition (95) have reached hammer prices that vary, but some recent examples show hammer prices of up to 40 euros (as seen in the December 2021 auction).

3. Starting price and estimates:
- The current starting price is 9 euros, and the average starting price in the past has been 11.24 euros.
- The estimated price for this auction is 15 euros, suggesting that bidders are willing to pay more than the starting price.

4. Sales trends: Of the 52 times it has been auctioned, it has sold on 24 occasions, indicating a consistent interest in the coin.

Based on these factors, a reasonable maximum purchase price could be in the range of 25 to 35 euros, considering that the condition is high and there is a history of hammer prices that supports this estimate. However, given the interest and demand, it may be wise to be prepared to bid up to 40 euros if competition is strong.

Therefore, an estimated maximum purchase price could be 35 euros.