To estimate a maximum purchase price for the coin to be auctioned, we will consider several factors, including the starting price, the condition of the coin, and the hammer prices of similar coins in the past.

1. Starting price: 25 euros.
2. Condition of the coin: 80 (Good Very Fine), indicating good preservation.
3. Previous hammer prices:
- In previous auctions, coins with a similar condition (80) have reached hammer prices of up to 190 euros.
- The average hammer prices for coins of similar condition seem to be in a range of 50 to 100 euros, depending on demand and other factors.

4. Auction trends:
- The coin has been auctioned 1,295 times, with a 75% sell-through rate, indicating good demand.
- The average hammer price for similar coins is approximately 98.9 euros.

Based on this data, an estimated maximum purchase price could be between 100 and 150 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate.

Therefore, a reasonable maximum purchase price could be 150 euros.