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

1. Coin Condition: The coin has a condition of 25 (BC), which is quite low. This generally implies that the final price will be significantly lower than that of coins in better condition.

2. Historical Data: By observing the final prices of coins with similar conditions, we can see that the final prices for coins in BC (Below Circulation) condition tend to be low. For example, in previous auctions, the final prices for coins with conditions of 30 or 25 have ranged from 15 to 36 euros.

3. Average Final Price: The average final price for this coin in the past has been 128.83 euros, but this includes coins in better conditions. For a coin with a condition of 25, it is reasonable to expect a much lower final price.

4. Starting Price: The starting price is 10 euros, which indicates that the seller is willing to accept a low offer, which may influence the final price.

5. Market Trends: Since the coin has been auctioned 266 times and has had a considerable number of sales (230), this suggests that there is consistent interest in this coin, but the low condition may limit that interest.

Based on these factors, an estimated maximum purchase price for this coin, considering its low condition and historical prices, could be between 15 and 30 euros. This reflects a range that is reasonable for a coin in BC condition, taking into account past auctions and market interest.