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 generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for this coin in the past is 529 euros.
- In recent auctions, we have seen hammer prices that vary significantly, ranging from 220 euros to 2800 euros, depending on the condition and demand at that time.
- In particular, at the March 2023 auction, the coin was hammered at 2800 euros, suggesting that there is significant interest in high-condition coins.

3. Starting Price and Average Starting Price:
- The current starting price is 500 euros, which is above the average starting price of 285.5 euros. This may indicate that the seller is confident that the coin will reach a higher price.

4. Recent Trends: In the most recent auctions, hammer prices have been quite high, suggesting that the market is willing to pay more for coins in good condition.

Based on these factors, an estimated maximum purchase price could be in the range of 800 to 1200 euros. This range takes into account the good condition of the coin, market interest, and previous hammer prices. However, given the history of high prices, it is possible that a buyer may be willing to pay even more if there is competition in the auction.