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

1. Starting price: 60 euros.
2. Condition: The coin is in a condition of 75 (MBC), indicating that it is in quite good shape.
3. Auction history: It has been auctioned 2 times in the past, of which it sold 1 time and did not sell 1 time. This suggests that there is interest in the coin, but also that there may be some resistance in the price.
4. Average hammer price: 100 euros, which is the average price it has sold for in the past.
5. Estimated price in previous auctions: In a previous auction, the estimated price was 70 euros, and the hammer price was 100 euros.

Given that the average hammer price is 100 euros and considering that the condition of the coin is good (75), a reasonable maximum purchase price could be in the range of the average hammer price.

Therefore, an estimated maximum purchase price could be 100 euros. However, since the starting price is 60 euros, buyers may be willing to pay a little more, but not necessarily up to the average hammer price. A range of 80 to 100 euros could be more realistic, depending on the competition in the auction.

In summary, an estimated maximum purchase price could be 100 euros, but with a more conservative approach, you might consider a range of 80 to 90 euros as a safer target.