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 for this coin is 111.38 euros, suggesting that, in general, buyers are willing to pay around this amount.
- In previous auctions, we have seen hammer prices that vary significantly, but there are examples of hammer prices exceeding 200 euros for coins of similar or better condition.

3. Starting Price and Average Starting Price:
- The current starting price is 18 euros, which is quite low compared to the average hammer price. This may indicate a good opportunity for buyers.

4. Recent Trends:
- In the most recent auctions, hammer prices have shown a range that can reach up to 80-120 euros for coins of similar condition.

Based on these factors, an estimated maximum purchase price for this coin could be between 120 and 150 euros. This is based on the auction price history and the current condition of the coin. However, it is important to keep in mind that the final price may vary depending on the competition in the auction and the interest of collectors at that time.