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

1. Current Condition: The coin has a condition of 75 (MBC), indicating that it is in an acceptable state, but not of the highest quality.

2. Auction History:
- The average hammer price in previous auctions is 190.03 euros, suggesting that, in general, coins of this reference tend to reach higher prices.
- However, it should also be noted that there have been auctions where the coin did not sell, which may indicate that interest can vary.

3. Previous Auction Prices:
- In previous auctions, hammer prices have varied significantly, ranging from 35.89 euros to 375.32 euros, depending on the condition and other factors.
- The last auction where the coin was sold with a condition of 75 had a hammer price of 35 euros, which is an indicator that interest may not be very high in this state.

4. Current Starting Price: The starting price is 50 euros, which is relatively low compared to the average hammer price.

5. Sales Trends: The coin has sold 50% of the times it has been auctioned, indicating moderate interest.

Based on these factors, an estimated maximum purchase price could be set in a range that considers both the starting price and the hammer price history. Given that the condition is 75 and considering the average hammer price, a reasonable maximum price could be:

Estimated maximum purchase price: 100 - 120 euros.

This range takes into account the condition and price history, allowing for some margin for competition in the auction.