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

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. Starting Price and Average Hammer Price: The starting price is 90 euros, and the average hammer price in previous auctions is 108.57 euros. This suggests that, in general, coins of this reference tend to sell for above their starting price.

3. Sales History: The coin has been auctioned 60 times, of which it has sold 57 times. This indicates a high sales rate, which can be a good indicator of demand.

4. Previous Prices: By looking at previous hammer prices for coins with similar conditions, we can see that in past auctions, coins with conditions ranging from 80 to 90 have reached hammer prices varying between 90 and 400 euros, depending on demand and other factors.

5. Recent Trends: In the most recent auctions, hammer prices have been in the range of 80 to 140 euros for similar conditions.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 120 to 150 euros. This is based on the good condition of the coin, the history of hammer prices, and the price trends in recent auctions.

Therefore, a reasonable maximum purchase price could be 150 euros.