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

1. Current Condition: The coin has a condition rating of 75 (MBC), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price in previous auctions for coins with a similar condition (75) has been approximately 29.88 euros.
- In past auctions, estimated prices for coins with a condition of 75 have ranged between 30 and 70 euros, with some hammer prices reaching up to 80 euros.

3. Starting Price: The current starting price is 40 euros, which is a good starting point.

4. Sales Trends: Of the 23 times it has been auctioned in the past, it has sold 8 times, indicating moderate interest in the coin.

5. Previous Prices: In the most recent auction, the hammer price was 80 euros, suggesting that there is potential to reach higher prices in the future.

Taking all these factors into account, an estimated maximum purchase price for this coin could be between 70 and 80 euros, given that the condition is good and there is a price history supporting this estimate. However, since the starting price is 40 euros, it may be wise to consider a more conservative purchase price, perhaps around 60-70 euros, depending on the competition in the auction.