To estimate a maximum purchase price for the coin in question, we will consider several factors:

1. Starting Price: 70 euros.
2. Condition: The coin has a condition rating of 70 (VF-), indicating that it is in relatively good shape.
3. Auction History:
- It has been auctioned 3 times in the past, of which it has sold 2 times and not sold 1 time.
- The average hammer price in previous auctions is 75 euros.
- The previous starting prices were 60 and 75 euros, with a hammer price of 75 euros in one of the auctions.

4. Average Starting and Hammer Price: The average starting price is 68.33 euros and the average hammer price is 75 euros.

Given that the coin is in good condition and has had a hammer price of 75 euros in the past, and considering that the current starting price is 70 euros, we can estimate that the maximum purchase price could be in a range above the starting price, but not too far above the average hammer price.

Therefore, an estimated maximum purchase price could be around 80-85 euros, taking into account the condition and auction history. This would allow for a competitive bid without exceeding the historical value of the coin too much.