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

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

2. Auction History:
- The average hammer price for similar coins in the past is 274.37 euros.
- The last auction for this coin had a hammer price of 600 euros, suggesting that there is significant interest in this particular coin.

3. Previous Starting and Hammer Prices:
- In previous auctions, hammer prices have varied, but there are examples of hammer prices exceeding 700 euros for coins of similar condition.
- The highest recorded auction for this coin was 1100 euros in 2020, although the condition of that coin is not specified.

4. Current Starting Price: The starting price is 600 euros, indicating that the seller has expectations of a high hammer price.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 700 to 800 euros, considering that the condition is good and there is a history of hammer prices supporting this estimate. However, given the interest in the coin and the starting price, a price of up to 900 euros could be reasonable when considering competition in the auction.