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. Previous Auction Prices: By looking at the hammer prices of coins with a similar condition (85), we can see that in the past, coins with this condition have reached hammer prices of up to 120 euros (as seen in the auction on 2020-09-17).

3. Average Hammer Price: The average hammer price for this coin is 99.5 euros, which is also a good indicator of the expected value.

4. Starting Price and Average Starting Price: The current starting price is 60 euros, and the average starting price is 69.47 euros. This suggests that the starting price is reasonable and could attract bidders.

5. Market Trends: Given that the coin has been auctioned 161 times and has had a good sales percentage (135 out of 161), this indicates a consistent interest in this coin.

Based on these factors, an estimated maximum purchase price could be around 120-130 euros, considering that the condition is good and there are precedents for hammer prices in that range. However, it is important to keep in mind that the final price will depend on the competition in the auction and the demand at that specific moment.