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 relatively good shape, but not among the highest quality.

2. Auction History:
- The average hammer price in previous auctions is 153.33 euros.
- In past auctions, hammer prices have varied significantly, with a maximum of 320 euros (for a coin with a condition rating of 85) and a minimum of 60 euros (for a coin with unspecified condition).

3. Starting Price and Average Starting Price:
- The current starting price is 50 euros, and the average starting price in previous auctions is 58 euros.

4. Sales Trends: The coin has been auctioned 9 times, of which it has sold 7 times, indicating good demand.

5. Proximity of Future Auctions: There is an auction scheduled in the coming days, which may influence demand and price.

Based on these factors, an estimated maximum purchase price could be in the range of 150 to 200 euros, considering that the coin's condition is good and that the auction price history suggests it could reach higher figures, especially if there is interest in the auction.

Therefore, a reasonable maximum purchase price could be 190 euros, aligning with the highest hammer price observed in previous auctions for coins of similar condition.