To estimate a maximum purchase price for the coin that will be auctioned, we can 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 (MBC+), indicating a fairly good condition.
3. Previous hammer prices:
- In previous auctions, coins with a similar condition (80) have reached hammer prices of up to 190 euros.
- Most hammer prices for coins in similar conditions range between 40 and 100 euros, depending on demand and other factors.

4. Average hammer price: 98.9 euros, suggesting that the hammer price could be considerably higher than the starting price.

5. Auction trends: Since it has been auctioned 1295 times and sold 971 times, there is good demand for this coin.

Based on this data, an estimated maximum purchase price could be in the range of 100 to 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.