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

1. Current Condition: The coin has a condition rating of 25 (BC), which indicates that it is not in very good shape. This generally reduces its value compared to coins in better condition.

2. Auction History:
- The average hammer price for similar coins in the past is 57.5 euros.
- The coin has been auctioned 11 times, of which it has sold 8 times, indicating good demand.
- Previous hammer prices varied, but there is a notable hammer price of 200 euros in 2020, although that was for a coin in better condition (75 condition rating).

3. Starting Price and Previous Prices:
- The current starting price is 35 euros, which is above the average starting price of 24.44 euros.
- The estimated hammer price in previous auctions has been up to 60 euros for coins in better condition.

Given that the condition of this coin is relatively low (25), and considering the hammer price history, a reasonable maximum purchase price could be in the range of 30 to 50 euros.

However, since the starting price is 35 euros and the trend of previous hammer prices, an estimated maximum purchase price could be 45 euros. This allows for some margin for competition in the auction, but also reflects the condition of the coin.