To estimate a maximum purchase price for the coin in question, we can analyze the provided data, including the starting price, the current condition of the coin, and the auction hammer prices from previous sales.

1. Current Condition: The coin has a condition of 75 (MS), indicating that it is in average state. This is important because coins in better condition tend to fetch higher prices.

2. Starting Price: The current starting price is 75 euros. This is a good starting point, but it does not necessarily reflect the true value of the coin.

3. Previous Hammer Prices: By looking at the hammer prices of coins with similar conditions (75-80), we can see that they have reached prices that vary considerably. For example:
- In 2014, a coin with a condition of 75 was sold for 191.25 euros.
- In 2022, a coin with a condition of 80 was sold for 135 euros.
- In 2023, a coin with a condition of 80 was sold for 232 euros.

4. Average Hammer Price: The average hammer price for this coin in the past is 297.92 euros, suggesting that, in general, coins of this reference tend to reach higher prices at auctions.

5. Auction Trends: Given that the coin has been auctioned 26 times and sold 23 times, there is good demand for this reference, which may influence the price.

Based on these factors, an estimated maximum purchase price could be between 150 and 250 euros, considering that the condition is 75 and that previous hammer prices have been significantly higher. A price of 200 euros could be a reasonable target, as it falls in the middle of this range and reflects the trend of previous hammer prices.