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

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

2. Auction History: By observing previous hammer prices for coins with similar conditions, we can see that:
- In past auctions, coins with a condition of 75 have reached hammer prices of up to 320 euros (in the case of the auction on 2022-02-24).
- The majority of hammer prices for conditions ranging from 70 to 90 have been in a range of 25 to 150 euros.

3. Average Hammer Price: The average hammer price for this coin is 68.89 euros, which can also serve as a reference.

4. Starting Price and Estimates: The current starting price is 18 euros, and the average starting price is 36.48 euros. This suggests that the market is willing to pay more than the starting price on many occasions.

5. Recent Trends: The coin has been auctioned 33 times, of which 27 have been successful sales. This indicates a consistent interest in the coin.

Based on these factors, an estimated maximum purchase price could be in the range of 100 to 150 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate. However, since the market can be volatile, it is advisable to keep an eye on the auction and adjust the bid according to the competition.