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 150 euros, and the average hammer price in previous auctions is 201.76 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 56 times, of which it has sold 54 times. This indicates high demand and good interest from collectors.

4. Previous Prices: Looking at previous hammer prices, we can see that in past auctions, coins with similar conditions have reached hammer prices that varied significantly, but some have exceeded 300 euros.

5. Recent Trends: In the most recent auctions, hammer prices have been quite high, with some reaching up to 420 euros.

Based on these factors, an estimated maximum purchase price could be in the range of 300 to 400 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate. A price of 350 euros could be a reasonable target, given the market context and observed demand.