To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Starting Price: 150 euros. This is the initial price set for the auction.
2. Condition: The coin has a condition rating of 70 (MBC-), indicating that it is in relatively good shape, although not of the highest quality (FDC).
3. Auction History: The coin has been auctioned 2 times in the past, and on both occasions, it has sold. The average hammer price in the past has been 650 euros, suggesting that there is significant interest in this coin.
4. Previous Prices: In the June 2022 auction, the coin was offered with a starting price of 120 euros and sold for 600 euros, indicating that the market is willing to pay much more than the starting price.

Given that the average hammer price has been 650 euros and considering that the current condition is slightly lower than that of the previous auction (75), we could adjust the estimated price downward.

Taking all these factors into account, an estimated maximum purchase price could be around 500-550 euros. This reflects interest in the coin but also takes into account its current condition and the established starting price.