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 quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History: By observing 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 45 and 170 euros, depending on demand and other factors.
- The average hammer price for coins with similar conditions seems to be around 70-90 euros.

3. Starting Price and Average Hammer Price: The current starting price is 30 euros, and the average hammer price in the past has been 49.04 euros. This suggests that there is considerable room for the final hammer price to be higher.

4. Recent Trends: In the most recent auctions, hammer prices have shown a trend of increasing, especially for coins in good condition.

Based on these factors, an estimated maximum purchase price for this coin could be between 80 and 120 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate.

Therefore, a reasonable maximum purchase price could be 100 euros.