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

1. Starting Price: 35 euros. This is the initial price set for the auction.
2. Condition: The coin has a condition rating of 75 (MBC), indicating that it is in good shape, but not a top-quality piece (FDC).
3. Auction History: The coin has been auctioned once and sold on that occasion, suggesting there is interest in the coin.
4. Average Hammer Price: Not provided, but since it has sold once, we could assume that the hammer price was similar to the starting price, given that there are no previous price data.

Since the condition is good (75 MBC) and it has a positive auction history, we could estimate that the hammer price might be slightly higher than the starting price, especially if there is interest in the coin.

Taking these factors into account, an estimated maximum purchase price could be in the range of 50 to 70 euros, depending on the demand at the auction. However, since there are no previous price data, it is difficult to be more precise. A reasonable maximum purchase price could be 60 euros.