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

1. Condition: The coin has a condition rating of 95 (S/C-), indicating that it is in very good shape. This generally increases its value compared to coins with lower conditions.

2. Auction history:
- The average hammer price for this coin has been 16.79 euros.
- In previous auctions, hammer prices have reached up to 75 euros (in December 2020) for coins with the same condition (95).
- Most auctions have had hammer prices ranging between 10 and 30 euros, depending on the condition.

3. Starting price and estimates:
- The current starting price is 15 euros, which is slightly higher than the average starting price of 9.41 euros.
- The estimated price for this auction is 25 euros, suggesting that there are expectations for the coin to sell at a higher price.

4. Recent trends: In the most recent auctions, hammer prices have been in the range of 15 to 40 euros for coins of similar condition.

Based on these factors, an estimated maximum purchase price could be in the range of 30 to 40 euros, considering that the condition is high and there is a history of hammer prices supporting this estimate. However, since the starting price is 15 euros, some bidders may choose not to exceed this price, which could influence the final outcome of the auction.

Therefore, a reasonable maximum purchase price could be 35 euros.