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. Price History: By observing the hammer prices of coins with similar conditions (95 and 100) in previous auctions, we can see that:
- In past auctions, coins with a condition of 100 have reached hammer prices of up to 85 euros.
- Coins with a condition of 95 have had hammer prices ranging between 19 and 36 euros.

3. Average Hammer Price: The average hammer price for this particular coin is 22.27 euros, which is also an indicator to consider.

4. Recent Trends: In the most recent auctions, the hammer price for coins with a condition of 95 has been between 16 and 25 euros.

Based on this data, an estimated maximum purchase price for the coin in question could be in the range of 30 to 40 euros, considering that the condition is high and there is a price history that supports this 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 considerable interest from collectors.

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