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-), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Starting Price and Average Hammer Price: The starting price is 1200 euros, and the average hammer price in previous auctions is 1310.81 euros. This suggests that, in general, coins of this reference tend to sell for above the starting price.

3. Auction History: In the auction history, it is observed that coins with a similar condition (85) have had hammer prices that vary, but many have exceeded 1300 euros. For example, in the auction on March 17, 2022, a coin with a condition of 85 was hammered at 1800 euros.

4. Recent Trends: In the most recent auctions, hammer prices have shown a trend of increasing, with a hammer price of 1900 euros in March 2024 for a coin with a similar condition.

Based on these factors, an estimated maximum purchase price could be in the range of 1600 to 1900 euros, considering that the average hammer price is 1310.81 euros and there are recent examples of higher hammer prices.

Therefore, a reasonable maximum purchase price could be 1800 euros. This allows for a margin to compete in the auction, given the price history and the condition of the coin.