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

1. Current 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 has been 21.79 euros.
- In previous auctions, we have seen hammer prices that varied, but there are examples of sales reaching up to 130 euros (in an auction with a condition of 100).
- Most hammer prices for similar conditions (95) have been in the range of 20 to 30 euros.

3. Starting Price and Average Starting Price: The current starting price is 12 euros, and the average starting price is 12.25 euros. This suggests that the starting price is reasonable and not excessively high.

4. Recent Trends: In the most recent auctions, hammer prices for coins with a condition of 95 have been around 16 to 30 euros.

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 that the price history shows there may be interest in paying more for coins in good condition. However, since the starting price is 12 euros, it is likely that the hammer price will not significantly exceed this range.

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