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 (MBC+), indicating good condition.
3. Previous hammer prices:
- In past auctions, coins with a similar condition (80) have reached hammer prices that varied considerably, but some relevant examples are:
- 190 euros (condition 80)
- 60 euros (condition 80)
- 55 euros (condition 80)
- 48 euros (condition 85)
- 42 euros (condition 85)

4. Average hammer price: 98.9 euros, which is significantly higher than the starting price.

5. Sales trends: The coin has been auctioned 1,295 times, of which it has sold 971 times, indicating good demand.

Based on this data, an estimated maximum purchase price could be between 80 and 120 euros, considering that the condition is good and the average hammer price is high. However, since the starting price is 25 euros, it is likely that buyers will be willing to pay a considerably higher price, but not necessarily reaching the highest previous hammer prices.

Final estimate: A reasonable maximum purchase price could be 100 euros.