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

1. Current Condition: The coin has a condition rating of 85 (ebc-), indicating that it is in quite good shape. This is important because coins in better condition tend to fetch higher prices.

2. Auction History:
- The average hammer price for similar coins in the past is 582.58 euros.
- In previous auctions, we have seen hammer prices that varied significantly, but there are examples of coins in similar conditions that have sold for significantly higher prices, such as 3800 euros in 2014.

3. Starting Price: The current starting price is 2000 euros, suggesting that the seller has expectations of a higher hammer price.

4. Price Trends: Observing the hammer prices of coins with similar conditions, it seems there is potential for this coin to reach a hammer price that exceeds the average price, especially considering that there have been recent auctions where coins in similar conditions have reached hammer prices of 660 euros.

Based on these factors, an estimated maximum purchase price could be in the range of 800 to 1200 euros, considering that the condition is good and there is a history of hammer prices suggesting that collectors are willing to pay more for coins in good condition. However, given the starting price of 2000 euros, it is possible that some bidders may be willing to go beyond this range, especially if there is interest in the coin.

Therefore, a reasonable maximum purchase price could be approximately 1200 euros.