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

1. Current 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. Auction History: By observing previous hammer prices for coins with similar conditions, we can see that the hammer price has varied. For example:
- In recent auctions, coins with a condition of 85 have reached hammer prices of 440 euros (2023-01-18) and 420 euros (2022-04-27).
- The general trend shows that the hammer price tends to be above the starting price, especially for coins in good condition.

3. Starting Price and Average Hammer Price: The current starting price is 350 euros, and the average hammer price for this coin is 356.18 euros. This suggests that the hammer price could be in a similar range or slightly higher.

4. Market Trends: Given that the coin has been auctioned 63 times and has had a high sales percentage (59 out of 63), this indicates a consistent interest in the coin, which may influence a higher hammer price.

Based on these factors, an estimated maximum purchase price could be in the range of 450 to 500 euros. This range takes into account the current condition, the auction price history, and the interest in the coin.