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 (MBC+/EBC-), which indicates that it is in quite good shape. This generally translates to a higher price compared to coins of lower condition.

2. Previous Auction Prices:
- In previous auctions, we have seen hammer prices that vary significantly. For example, in the March 2023 auction, a coin with a condition of 95 sold for 34,000 euros, indicating a strong market for high-quality coins.
- In other auctions, hammer prices have ranged between 2,500 and 8,000 euros for similar conditions (85).

3. Average Hammer Price: The average hammer price for this coin is 8,907.14 euros, suggesting that, in general, buyers are willing to pay a considerably higher price than the starting price.

4. Starting Price and Average Starting Price: The starting price is 2,000 euros, and the average starting price is 2,900 euros. This indicates that the current starting price is relatively low compared to the average hammer price.

Based on these factors, an estimated maximum purchase price could be in the range of 8,000 to 10,000 euros, considering that the condition is good and that interest in quality coins seems to be high. However, since the highest hammer price in the past was 34,000 euros, it is possible that some buyers may be willing to pay more, but this will depend on the competition in the auction and the interest of collectors at that time.

Therefore, a reasonable maximum purchase price could be approximately 9,000 to 10,000 euros.