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

1. Starting Price: 70 euros. This is the initial price of the auction.
2. Condition: The coin has a condition rating of 75 (MBC), indicating that it is in an acceptable state, but not excellent.
3. Auction History:
- It has been auctioned 3 times in the past, of which it has sold 2 times.
- The average hammer price in previous auctions is 328 euros, suggesting that, despite a lower starting price, interest in the coin may be high.
4. Previous Prices: In the June 2022 auction, the coin sold for 328 euros with a condition rating of 85, which is higher than the current one.

Given that the current condition is 75, and considering that the average hammer price is significantly higher than the starting price, we can estimate that the hammer price could be in a lower range than 328 euros, but still considerably higher than the starting price.

Taking all these factors into account, an estimated maximum purchase price could be between 200 and 250 euros, depending on collector interest and competition in the auction. This is based on the price history and the current condition of the coin.