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

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

2. Historical Prices: By looking at previous auction prices, we can see that the coin has reached auction prices of up to 130 euros in similar conditions (condition of 85) and 95 euros in other auctions.

3. Average Auction Price: The average auction price for this coin is 52.58 euros, which is also a good indicator of the expected value.

4. Auction Trends: The coin has been auctioned 20 times, of which 14 have sold. This suggests that there is consistent interest in the coin, which may increase its value.

5. Starting Price: The starting price is 25 euros, which is relatively low compared to previous auction prices.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 80 to 100 euros, given that the condition is good and there are precedents for higher auction prices in the past. However, to be more conservative and considering the average auction price, a reasonable maximum purchase price could be approximately 85 euros.