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 fairly good shape, but not the best possible condition. This may influence the price, as coins in better condition tend to fetch higher prices.

2. Current Starting Price and Previous Prices: The current starting price is 600 euros, and the average hammer price in previous auctions is 1437 euros. This suggests that, in general, coins of this reference tend to sell for a significantly higher price than their starting price.

3. Auction History: The auction history shows that on several occasions the coin has reached hammer prices that exceed the starting price. For example, in the 2020 auction, the hammer price was 1100 euros with a starting price of 450 euros. This indicates that there is considerable interest in this coin.

4. Price Trends: The average hammer price of 1437 euros is a good indicator of what buyers are willing to pay. However, given that the current condition is 85, it is reasonable to adjust this price downward.

5. Comparison with Previous Prices: The coin has had hammer prices that vary, but overall, the hammer prices have been in a range that suggests the price of 1437 euros is achievable, although it may not be reached in this specific auction due to the condition.

Taking all these factors into account, an estimated maximum purchase price could be around 1200-1300 euros. This reflects interest in the coin, but also considers its condition and the fact that the hammer price may vary depending on competition in the auction.