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

1. Current Condition: The coin has a condition of 75 (VF), indicating that it is in a medium-low state of preservation. This may influence the price, as coins in better condition tend to reach higher prices.

2. Previous Hammer Prices: Looking at the hammer prices from previous auctions for coins with similar conditions:
- In 2019, a coin with a condition of 75 was sold for 170 euros.
- In 2021, another coin with a condition of 75 was sold for 240 euros.
- In 2022, a coin with a condition of 95 was sold for 650 euros, but this is an exceptional case due to its better condition.

3. Starting Price and Average Hammer Price: The current starting price is 300 euros, and the average hammer price in the past has been 278.13 euros. This suggests that the starting price is relatively high compared to the average hammer price.

4. Auction Trends: Given that the coin has been auctioned 33 times and has had a high sales percentage (31 out of 33), this indicates a consistent interest in this coin.

5. Estimation: Based on the current condition and previous hammer prices, a reasonable maximum purchase price could be in the range of 200 to 250 euros. This is because, although the starting price is 300 euros, the average hammer price and previous conditions suggest that a lower price would be more realistic for a coin in VF condition.

Therefore, an estimated maximum purchase price could be 250 euros.