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 in lower condition.

2. Current Listing Price and Previous Prices: The current listing price is 1600 euros, which is above the average listing price of 1263.75 euros. However, the average hammer price is 1774.42 euros, suggesting that similar coins have reached higher prices in previous auctions.

3. Sales History: The coin has been auctioned 13 times in the past, with 12 successful sales. This indicates a consistent interest in the coin, which may influence its price.

4. Previous Hammer Prices: Looking at previous hammer prices, the coin has reached prices of up to 1500 euros in recent auctions, although it has also had lower hammer prices. The trend seems to be that prices have been increasing over time, especially for coins in better condition.

5. Comparison with Similar Coins: The last auction of a similar coin with a condition of 95 reached a hammer price of 9500 euros, indicating that there is a market for high-quality coins.

Taking all these factors into account, an estimated maximum purchase price could be around 2000 euros. This is based on the fact that the condition is good, interest in the coin is high, and previous hammer prices suggest potential for reaching higher prices in the future. However, it is important to consider that the final price will depend on competition in the auction and demand at that time.