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 may positively influence its price.

2. Auction History:
- The average hammer price for similar coins is 126.75 euros.
- In previous auctions, we have seen hammer prices that varied significantly, ranging from 40 euros to 480 euros, depending on the condition and other factors.

3. Starting Price and Previous Sales:
- The current starting price is 40 euros, and there have been 10 previous auctions, of which 8 resulted in sales. This suggests a consistent interest in the coin.
- The average starting price of 57.78 euros also indicates that the current starting price is relatively low compared to the average.

4. Recent Trends: In the most recent auction, a coin with a similar condition (75) was sold for 110 euros. This suggests that the market is willing to pay higher prices for coins in good condition.

5. Sales Ratio: Given that 80% of the coins auctioned in the past have sold, this indicates good demand.

Based on these factors, an estimated maximum purchase price could be in the range of 100 to 130 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate.

Therefore, a reasonable maximum purchase price could be 120 euros.