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

1. Starting Price: 40 euros. This is the initial price set for the auction.
2. Condition: The coin has a condition rating of 75 (MBC - Very Good Condition), indicating that it is in quite good shape. Generally, coins in better condition tend to fetch higher prices at auctions.
3. Auction History: The coin has been auctioned once and sold on that occasion, suggesting that there is interest in it. There have been no failed sale attempts, which is a positive sign.
4. Average Hammer Price: An average hammer price is not provided, making it difficult to assess market interest in this particular coin.

Given that the starting price is 40 euros and considering that the condition is good, we could estimate that the hammer price might be slightly higher than the starting price, especially if there is interest in the coin.

A reasonable approach would be to consider a 20-30% increase over the starting price, given the condition and auction history.

Therefore, an estimated maximum purchase price could be in the range of:

- Estimated Maximum Purchase Price: 48 - 52 euros.

This is just an estimate, and the actual price may vary depending on demand at the auction.