To estimate a maximum purchase price for the coin in question, let's consider several factors:

1. Condition: The coin has a condition rating of 95 (S/C-), indicating that it is in very good shape. This generally increases its value compared to coins with lower conditions.

2. Auction history:
- The average hammer price in previous auctions is approximately 300.88 euros, suggesting that this is a reasonable price to expect.
- In the most recent auction (2024-03-14), the coin was auctioned with a starting price of 125 euros and a hammer price of 300 euros, indicating that interest in this coin remains strong.

3. Previous hammer prices:
- In 2020, the coin sold for 1200 euros, but this may be an exceptional case due to the high condition (100) of that particular coin.
- In other auctions, hammer prices have varied, but they have generally remained in a range of 140 to 420 euros for similar conditions.

4. Current starting price: The starting price is 300 euros, indicating that the seller expects the coin to sell within that range.

Based on these factors, an estimated maximum purchase price could be between 400 and 600 euros, considering that the condition is high and that interest in the coin seems to be maintained. However, since the average hammer price is approximately 300.88 euros, a more conservative purchase price could be around 400 euros, while a more optimistic price could go up to 600 euros if there is competition in the auction.