To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially considering the coin's condition (95 - EBC+) and previous auction prices.

1. Condition: The coin has a condition 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. Previous auction prices: By observing the auction prices of coins with the same condition (95), we can see that they have reached auction prices of up to 550 euros in recent auctions. For example:
- In 2024, a coin with a condition of 95 was auctioned for 550 euros.
- In 2022, another coin with the same condition was auctioned for 480 euros.

3. Starting price and average auction price: The current starting price is 400 euros, and the average auction price in the past has been approximately 369.35 euros. However, given that the condition is high, it is reasonable to expect that the auction price will be above this average.

4. Auction trends: Since the coin has been auctioned 25 times and all have been sold, this indicates a consistent interest in the coin, which may increase its value.

Based on these factors, an estimated maximum purchase price could be between 500 and 600 euros, considering that the condition is excellent and there are precedents for high auctions in the past. Therefore, a reasonable maximum purchase price could be 550 euros.