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

1. Current Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in relatively good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Current Starting Price and Previous Prices: The current starting price is 600 euros, which is significantly higher than the average starting price of 330.36 euros. However, the average hammer price is 477.43 euros, suggesting that similar coins have performed well in previous auctions.

3. Sales History: Out of the 14 times this coin has been auctioned, it has sold 7 times, indicating a consistent interest in the coin. This is a good indicator that there may be competition in the auction.

4. Previous Hammer Prices: Looking at previous hammer prices, the highest recorded price was 750 euros in 2014, while other recent hammer prices have been lower, but still in the range of 400-450 euros.

5. Market Trends: Given that the coin's condition is relatively high and considering the interest in past auctions, it is reasonable to assume that the price could be in the upper range of previous hammer prices.

Based on these factors, an estimated maximum purchase price could be between 600 and 750 euros. However, since the starting price is 600 euros, a more conservative maximum purchase price could be around 700 euros, which would allow for competition without exceeding the starting price.

Therefore, the estimated maximum purchase price would be 700 euros.