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

1. Current Condition: The coin has a condition of 75 (VF), which is a medium-low condition. This suggests that the auction price could be lower than that of coins in better condition.

2. Previous Auction Prices:
- In the past, coins with a similar condition (75) have had auction prices that vary significantly. For example, in previous auctions, the auction prices for coins with a condition of 75 have ranged between 170 and 700 euros, depending on other factors such as demand and rarity of the coin.

3. Average Auction Price: The average auction price for this coin is 406.31 euros, indicating that, in general, coins of this reference tend to sell for relatively high prices.

4. Starting Price: The current starting price is 175 euros, which is quite low compared to the average auction price.

5. Estimation: Given that the condition is 75 and considering the previous auction prices, a reasonable maximum purchase price could be in the range of 300 to 400 euros. This is based on the fact that, although the coin is not in the best condition, its demand and price history suggest it could reach a higher price than the starting price.

Therefore, an estimated maximum purchase price for this coin could be approximately 350 euros.