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 is important because coins in better condition tend to fetch higher prices.

2. Auction History:
- The average hammer price for similar coins has been 54.4 euros.
- In previous auctions, hammer prices for coins with a similar condition (75) have varied, but there are examples of sales reaching up to 90 euros (as seen in the auction on March 1, 2023).

3. Starting Price and Average Starting Price: The starting price is 40 euros, and the average starting price is 36 euros. This suggests that the starting price is reasonable and could attract bidders.

4. Sales Trends: The coin has been sold in 11 out of the last 12 auctions, indicating good demand.

5. Previous Estimates: In past auctions, the estimated price has been as high as 90 euros, suggesting there is potential for a higher hammer price.

Considering all these factors, an estimated maximum purchase price could be around 80-90 euros, given that the condition is good and there is a history of hammer prices supporting this figure. However, to be conservative and considering the starting price, a safer maximum purchase price could be approximately 75-80 euros.