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

1. Condition: The coin has a condition rating of 75 (MBC), indicating that it is in quite good shape. This generally increases its value compared to coins in lower condition.

2. Auction History:
- It has been auctioned 5 times in the past, of which it has sold 4 times. This suggests that there is consistent interest in the coin.
- The average hammer price in previous auctions is 97.5 euros, indicating that, in general, buyers are willing to pay close to this price for similar coins.

3. Previous Starting and Hammer Prices:
- In previous auctions, starting prices have varied, but the highest hammer price was 125 euros in 2014, which sets a precedent for the value of the coin in good condition.
- The current starting price is 40 euros, which is relatively low compared to the average hammer price.

4. Market Trends: Since the average hammer price is significantly higher than the current starting price, this suggests that there is potential for the coin to sell at a higher price.

Taking all these factors into account, an estimated maximum purchase price could be around 100-120 euros, considering that the condition is good and that interest in the coin appears to be solid. This also aligns with the average hammer price in previous auctions.