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

1. Current Condition: The coin has a condition of 85 (MS+/EF-), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Historical Prices: By looking at previous auction 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 50 and 245 euros, depending on demand and other factors.
- The average hammer price for coins with a similar condition (85) could be in the range of 80 to 100 euros, based on historical data.

3. Starting Price and Average Hammer Price: The current starting price is 30 euros, and the average hammer price in the past has been 86.58 euros. This suggests that the hammer price could be significantly higher than the starting price.

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 90 and 120 euros. This is due to the good condition of the coin and the historical hammer prices of similar coins. However, the final price will depend on the competition in the auction and the specific demand at that time.