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

1. Condition: The coin has a condition of 85 (ebc-), which indicates that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Previous auction prices: By looking at the auction prices of coins with a similar condition (85), we can see that they have reached auction prices of up to 110 euros in recent auctions. For example, at the auction on 2023-01-18, a coin with a condition of 95 was sold for 110 euros, and at the auction on 2018-10-17, a coin with a condition of 85 was sold for 75 euros.

3. Average auction price: The average auction price for this coin is 63.5 euros, which is also an important indicator.

4. Auction trends: The coin has been auctioned 77 times, with a high sales percentage (69 out of 77). This suggests that there is consistent interest in this coin, which may influence its price.

5. Starting prices and estimates: The current starting price is 25 euros, and the average starting price is 37 euros. This suggests that the final auction price could be above these values, especially considering the condition.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 80-100 euros. This is based on the condition, previous auction prices, and general interest in the coin. However, it is important to remember that the final price may vary depending on competition in the auction and other market factors at the time of sale.