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 85 (ebc-), indicating that it is in quite good shape. In the past, coins with a similar condition have reached auction prices that vary, but they generally fall within a range of 40 to 60 euros.

2. Previous Auction Prices: By observing the auction prices of coins with a condition of 85, we can see that they have reached auction prices of up to 60 euros on several occasions. For example, in previous auctions, coins with a condition of 85 have sold for 40, 45, and 60 euros.

3. Average Auction Price: The average auction price for this coin is 47.86 euros, which also suggests that an auction price around this value is reasonable.

4. Starting Price and Recent Auction Prices: The starting price is 25 euros, and the average starting price is 34.28 euros. This indicates that there is interest in the coin, and since it will be auctioned in the coming days, it is likely that the final auction price will be higher than the starting price.

5. Market Trends: Given that there are 4 similar coins that will be auctioned in the coming days, this could influence competition and, therefore, the final price.

Taking all these factors into account, an estimated maximum purchase price for this coin could be between 60 and 70 euros. This is based on the analysis of previous auction prices and the condition of the coin. Therefore, a reasonable maximum purchase price could be 70 euros.