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

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

2. Auction History: By looking at previous hammer prices for coins with similar conditions (around 80), we can see that hammer prices have varied. For example, in recent auctions, coins with a condition of 80 have reached hammer prices of up to 110 euros.

3. Average Hammer Price: The average hammer price for this coin is 75.57 euros, which provides a good reference for the expected value.

4. Starting Price and Previous Prices: The current starting price is 25 euros, and the average starting price is 53.19 euros. This suggests that the market is willing to pay more than the starting price.

5. Market Trends: Since it has been auctioned 205 times and sold 170 times, there is a consistent demand for this coin, which may increase its value.

Based on these factors, an estimated maximum purchase price for this coin could be between 100 and 120 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate.