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

1. Coin Condition: The coin has a condition rating of 95 (S/C-), 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 in the past has been 19.56 euros.
- In previous auctions, coins with a condition of 95 have reached hammer prices that varied, but some examples are:
- 22 euros in December 2020.
- 20 euros in September 2022.
- 30 euros in December 2024.

3. Starting Price and Estimated Prices:
- The current starting price is 12 euros, and the estimated price is 20 euros.

4. Sales Trends: The coin has been sold in 45 out of 55 auctions, indicating good demand.

Based on these factors, an estimated maximum purchase price could be in the range of 25 to 30 euros, considering that the condition is high and that similar prices have been reached in previous auctions. Therefore, a reasonable maximum purchase price could be 30 euros.