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 this coin in the past has been 19.46 euros.
- In previous auctions, coins with a similar condition (95) have reached hammer prices that vary, but some examples are:
- 20 euros on 2022-09-14.
- 22 euros on 2020-12-14.
- 20 euros on 2018-10-16.
- The highest recorded auction for a coin in condition 100 was 80 euros, but that is an exceptional case.

3. Starting Price and Estimates:
- The current starting price is 12 euros, and the average starting price in the past has been 11.51 euros.
- The estimated price for this auction is 20 euros.

4. Sales Trends: The coin has been sold in 43 out of 54 auctions, indicating good demand.

Based on these factors, a reasonable maximum purchase price could be in the range of 25 to 30 euros, considering that the condition is high and that the price history shows similar coins have reached hammer prices in that range.

Therefore, an estimated maximum purchase price could be 30 euros.