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

1. Starting price: 60 euros.
2. Current condition: 25 (BC), indicating that the coin is in quite low condition.
3. Auction history:
- In 2017, the coin was auctioned with a starting price of 60 euros and sold for 131 euros, indicating significant interest despite the low condition.
- In 2024, it was auctioned with a starting price of 100 euros and an estimated price of 180 euros, but it did not sell, which could indicate that the condition or the starting price was not attractive to buyers.

4. Average hammer price: 131 euros, which is a good indicator of the value that buyers were willing to pay in the past.

Given that the current condition is low (25), it is likely that the hammer price will not reach the levels of coins in better condition. However, the interest in the coin in previous auctions suggests that there may be a market for it.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 80 to 100 euros. This is based on the interest shown in previous auctions and the fact that, although the condition is low, there is a price history that suggests some buyers are willing to pay more than the starting price.

Therefore, a reasonable maximum purchase price could be 90 euros.