To estimate a maximum purchase price for the coin in question, we can analyze the provided data and consider several factors:

1. Coin Condition: The coin to be auctioned has a condition rating of 80 (MBC+). This is an important factor, as coins in better condition tend to fetch higher prices.

2. Previous Auction Prices:
- The coin has been auctioned several times with starting prices ranging from 600 to 900 euros.
- Previous hammer prices (when sold) have reached up to 1600 euros in the most recent case (2024) for a coin with a condition rating of 95, indicating that the market may be willing to pay high prices for quality coins.

3. Average Hammer Price: The average hammer price for previous auctions is 1030 euros, suggesting that, in general, coins of this reference tend to sell above their starting price.

4. Sales Trends: Of the 8 times it has been auctioned, it has sold on 4 occasions, indicating interest in the coin, but also that there is a 50% non-sale rate in the past, which may influence the perception of value.

5. Estimated Price: The estimated starting price for this auction is 600 euros, which is relatively low compared to previous hammer prices.

Based on these factors, an estimated maximum purchase price could be in the range of 1000 to 1200 euros, considering that the condition is good (80) and that there seems to be interest in the coin. However, since the highest hammer price in the past has been 1600 euros, it is possible that a buyer may be willing to pay a bit more if competition is high at the auction.

Therefore, a reasonable maximum purchase price could be 1200 euros.