To estimate a maximum purchase price for the coin in question, we can analyze 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:
- The coin has been auctioned 17 times, of which 11 have been successful sales. This suggests there is consistent interest in the coin.
- The average hammer price in previous auctions is 51.71 euros, providing a benchmark.

3. Starting and Hammer Prices:
- The current starting price is 60 euros, which is higher than the average starting price of 44.9 euros in previous auctions.
- Previous hammer prices for coins in similar conditions (85) have varied, but there are examples of auctions that have reached up to 98.66 euros in similar condition.

4. Recent Trends: In the most recent auctions, hammer prices have ranged from 55 to 69 euros for coins with a condition of 90, suggesting that interest and value for the coin are on the rise.

Based on these factors, an estimated maximum purchase price could be set in a range between 70 and 90 euros, considering that the coin's condition is good and there is a history of hammer prices supporting this estimate.

Therefore, a reasonable maximum purchase price could be 80 euros.