To estimate a maximum purchase price for the coin that is going to be auctioned, we can consider several factors, including the coin's condition, previous auction prices, and the average auction price.

1. Coin Condition: The coin in question has a condition rating of 80 (MBC+). This indicates that it is in relatively good shape, which can positively influence its price.

2. Previous Auction Prices: By looking at previous auction prices for coins with a similar condition (80), we can see that they have reached auction prices that vary considerably. For example, in previous auctions, coins with a condition of 80 have reached auction prices of up to 190 euros.

3. Average Auction Price: The average auction price for this coin is 98.9 euros, which is also a good indicator of the expected value.

4. Starting Price: The starting price of the auction is 25 euros, suggesting that there is considerable room for the final price to be higher.

5. Market Trends: Since the coin has been auctioned 1,295 times and has had a high number of sales (971), this indicates sustained interest in this coin, which may increase its value at auction.

Based on these factors, an estimated maximum purchase price could be in the range of 150 to 200 euros, considering that the condition is good and there are precedents for high auction prices for similar coins. However, since the market can be volatile, it is advisable to stay alert to the dynamics of the auction and adjust the bid accordingly.