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 in the past has been 25.96 euros.
- The coin has been auctioned 33 times, of which it has sold 28 times, indicating good demand.
- In recent auctions, hammer prices have varied, but some have reached up to 45 euros for similar conditions.

3. Starting Price: The current starting price is 30 euros, which is slightly higher than the average starting price of 18.34 euros. This may indicate that the seller is confident that the coin will fetch a good price.

4. Recent Trends: In the most recent auctions, hammer prices have shown an increase, especially for coins in good condition. For example, in 2022, coins with similar conditions sold for prices around 30-35 euros.

Based on these factors, an estimated maximum purchase price could be between 40 and 50 euros, considering that the condition is good and there is an upward trend in hammer prices for similar coins. However, it is important to keep in mind that the final price will depend on the competition in the auction and the interest of other buyers.