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

1. Coin Condition: The coin has a condition rating of 95 (EBC+), indicating that it is in very good condition. 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 a similar condition (95), we can see that they have reached auction prices of up to 650 euros in the past (as seen in the auction on 2021-12-16).

3. Average Auction Price: The average auction price for this coin is 116.27 euros, but given the high condition, we can expect the auction price to be above this average.

4. Starting Price and Recent Auction Prices: The current starting price is 225 euros, suggesting that the seller has expectations of a higher auction price. Additionally, the average starting price of 80.21 euros and the number of times it has been sold (63) indicate that there is consistent interest in this coin.

5. Auction Trends: Since it has been auctioned 81 times and sold 63 times, there is a good conversion rate, suggesting that there is demand for this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 300 to 400 euros, considering that the condition is high and there are precedents for higher auction prices in the past. However, given the starting price of 225 euros, it is likely that buyers will be willing to bid more, especially if there is interest in the auction.

Therefore, a reasonable maximum purchase price could be 350 euros.