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

1. Condition: The coin has a condition rating of 70 (VF-), indicating that it is in quite good shape. This can positively influence its value.

2. Starting and hammer price: The current starting price is 300 euros, and the average hammer price in previous auctions is 93.75 euros. However, in the most recent auction (2023-03-16), the coin sold for 180 euros, suggesting there is interest in this price range.

3. Auction history: The coin has been auctioned 7 times, of which it has sold 4 times. This indicates that there is an active market for this coin, although there is also a significant number of auctions where it did not sell.

4. Previous prices: In the 2023 auction, the hammer price was 180 euros, and in the 2024 auction, the starting price was 250 euros, suggesting that the value of the coin has fluctuated but remains in a relatively high range.

5. Average starting price: The average starting price of 145.5 euros and the average hammer price of 93.75 euros are also important indicators to consider.

Given all this, an estimated maximum purchase price could be set in a range between 180 and 250 euros, considering that the current starting price is 300 euros, but the actual market interest seems to be closer to 180 euros, which was the hammer price in the most recent auction.

Therefore, a reasonable estimated maximum purchase price could be 200 euros. This allows for some competition in the auction while also aligning with previous hammer prices.