To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the current condition of the coin.

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

2. Previous Auction Prices: By observing the auction prices of coins with similar conditions (around 80-90), we can see that:
- In several auctions, coins with a condition of 85 have reached hammer prices ranging from 400 to 1300 euros.
- For example, in a 2020 auction, a coin with a condition of 85 sold for 1400 euros, and in another auction in 2022, a coin with a condition of 85 sold for 1550 euros.

3. Starting Price and Average Hammer Price: The starting price of the coin is 1500 euros, and the average hammer price for similar coins is 633.41 euros. However, since the starting price is quite high, bidders are likely to be willing to pay more if the coin is attractive.

4. Auction Trends: The coin has been auctioned 37 times in the past, with a high sales percentage (33 out of 37). This suggests that there is consistent interest in this coin, which may increase its value in the current auction.

5. Maximum Price Estimation: Based on the condition, previous hammer prices, and interest in the coin, a reasonable maximum purchase price could be in the range of 1200 to 1600 euros. This aligns with previous hammer prices for coins of similar condition and the current starting price.

Therefore, an estimated maximum purchase price for this coin could be 1600 euros.