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

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

2. Previous Auction Prices: By observing the hammer prices of coins with a similar condition (95), we can see that they have reached varying hammer prices. For example:
- In the auction on 2021-12-16, a coin with a condition of 95 was sold for 40 euros.
- In other auctions, the hammer prices for coins with a condition of 95 have ranged from 10 to 30 euros.

3. Average Hammer Price: The average hammer price for this particular coin is 17.29 euros, which is also a useful indicator.

4. Starting Price: The starting price is 15 euros, suggesting that the seller expects a reasonable price for the coin.

5. Auction Trends: Given that there have been 52 auctions for this coin and 24 have resulted in sales, there is considerable interest in this coin, which may influence the price.

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 are precedents for sales in that range. However, since the starting price is 15 euros, it is likely that the hammer price will not significantly exceed this range unless there is strong competition among bidders.

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