To estimate a maximum purchase price for the coin in question, we will consider several factors:

1. Coin Condition: The coin has a condition rating of 85 (MBC+/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 looking at previous hammer prices for coins with similar conditions (around 80-90), we can see that hammer prices have varied. For example:
- In previous auctions, coins with a condition of 85 have reached hammer prices of up to 90 euros.
- The average hammer price for coins of similar condition seems to be around 80-90 euros.

3. Starting Price and Average Hammer Price: The current starting price is 60 euros, and the average hammer price in the past has been 84.29 euros. This suggests that the hammer price could be in a similar range or slightly higher.

4. Recent Trends: In the most recent auctions, hammer prices for coins of similar condition have shown a range of 70 to 110 euros, indicating a growing interest in coins in good condition.

Based on these factors, an estimated maximum purchase price for this coin could be between 90 and 110 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.