To estimate a maximum purchase price for the coin in question, we can 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. Current Listing Price and Previous Prices: The current listing price is 90 euros. In previous auctions, we have seen hammer prices that vary significantly, but there are examples of coins with similar conditions that have sold for higher prices. For instance, in past auctions, coins with a condition of 85 have reached hammer prices of up to 130 euros.

3. Price Trends: The average hammer price for this coin is 96.24 euros, suggesting that buyers are willing to pay a bit more than the listing price on average.

4. Analysis of Previous Prices: By looking at the hammer prices of coins with similar conditions, we can see a range from 70 euros to 340 euros, depending on demand and other market factors.

Based on these points, an estimated maximum purchase price for this coin could be in the range of 120 to 150 euros. This is based on the condition, the listing price, and previous hammer prices for similar coins. However, it is important to keep in mind that the final price may vary depending on competition in the auction and the interest of collectors.