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-). This is an important factor, as coins in better condition tend to reach higher prices.

2. Auction History:
- The average hammer price for similar coins has been 129.69 euros.
- In the past, coins with a similar condition (85) have reached hammer prices that varied, but there are examples of auctions in the range of 56 to 190 euros.

3. Starting Price: The starting price is 40 euros, indicating that the seller expects a lower price initially, but this does not necessarily reflect the actual value of the coin.

4. Price Trends: Observing previous hammer prices, there is a trend for coins with conditions ranging from 85 to 90 to sell in a range of 70 to 150 euros, depending on demand and other market factors.

5. Average Starting and Hammer Prices: The average starting price of 88.71 euros and the average hammer price of 129.69 euros suggest that there is a considerable margin between what is expected and what is actually paid.

Based on these factors, an estimated maximum purchase price for the coin could be in the range of 100 to 150 euros, considering that the condition is good and there is a price history that supports this estimate.

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