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 (EBC+), indicating that it is in very good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History: By looking at previous auction prices for coins with similar conditions (95 and 100), we can see that the hammer price has varied. For example:
- In 2019, a coin with a condition of 95 was sold for 30 euros.
- In 2020, a coin with a condition of 100 was sold for 65 euros.
- In 2022, a coin with a condition of 95 was sold for 25 euros.

3. Average Hammer Price: The average hammer price for this coin is 20.03 euros, providing a reference point.

4. Starting Price and Estimates: The current starting price is 12 euros, and the average starting price is 11.63 euros. However, the estimated price for this auction is 20 euros.

5. Recent Trends: In the most recent auctions, hammer prices have shown a trend of increasing, especially for coins in good condition.

Based on these factors, an estimated maximum purchase price for this coin could be between 30 and 40 euros, considering that the condition is high and there is a history of hammer prices that supports this estimate. However, since the starting price is 12 euros, buyers may be willing to pay a bit more, but not necessarily reaching 40 euros. A reasonable maximum price could be 35 euros.