Based on the provided data, here is an analysis to estimate a maximum purchase price for the coin in question:

1. Starting Price: 1500 euros. This is the initial price set for the auction.
2. Auction History: The coin has been auctioned once and sold on that occasion, indicating that there is interest in the coin.
3. Condition: The coin has a condition rating of 75 (MBC), suggesting that it is in fairly good shape, although not the best possible condition.
4. Average Hammer Price: The average hammer price is equal to the starting price, indicating that the coin sold for the initial price in the only previous auction.

Given that the coin has a history of successful sale and a reasonable condition, we could estimate a maximum purchase price that might be slightly higher than the starting price, considering that collectors may be willing to pay a bit more for a coin in good condition.

Estimated Maximum Purchase Price: It could be reasonable to consider a maximum purchase price between 1800 and 2000 euros, depending on the interest of collectors and competition in the auction. This is based on a 20-30% increase over the starting price, which is common in coin auctions with a positive history.