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 fairly good shape, but not the best possible condition.

2. Auction History:
- The average hammer price for this coin in the past has been 42.55 euros.
- In previous auctions, hammer prices have varied, with some reaching up to 110 euros in optimal conditions (condition rating 100).
- Most hammer prices for coins with a similar condition (85) have been in the range of 25 to 60 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 15 euros, which is relatively low compared to the average starting price of 30.64 euros.

4. Recent Trends:
- In the most recent auctions, hammer prices for coins with a similar condition have been around 30 to 50 euros.

Based on these factors, an estimated maximum purchase price for this coin could be between 50 and 70 euros. This is because, although the condition is not the highest, the price history and current trend suggest that collectors would be willing to pay a reasonable price for a coin in good condition.

Therefore, a reasonable maximum purchase price could be 70 euros.