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

1. Current condition: The coin has a condition rating of 85 (ebc-), which indicates that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction history: The coin has been auctioned 27 times, of which it has sold 25 times. This suggests that there is a consistent demand for this coin. The average hammer price in the past has been 232.22 euros, which is a good indicator of the market value.

3. Previous auction prices: By looking at the hammer prices from previous auctions, we can see that prices have varied, but there are several examples of auctions that exceeded 200 euros, even reaching up to 400 euros on some occasions.

4. Starting price: The current starting price is 150 euros, which is relatively low compared to the average hammer price.

Taking these factors into account, an estimated maximum purchase price could be in the range of 250 to 300 euros, as this aligns with previous hammer prices and the good condition of the coin. However, it is important to consider that the final price may vary depending on the competition in the auction and the interest from other buyers.