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

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

2. Starting Price and Hammer Price: The current starting price is 75 euros, and the average hammer price in previous auctions is 141.96 euros. This suggests that, in general, coins of this reference tend to sell for a significantly higher price than their starting price.

3. Auction History:
- In the past, there have been auctions with hammer prices that varied considerably. For example, in 2015, a coin with a similar condition sold for 160 euros.
- There are also examples of coins with a condition of 75 that have sold for prices ranging from 50-100 euros in previous auctions.

4. Sales Trends: Of the 16 times it has been auctioned, it has sold 10 times, indicating a reasonable sell-through rate. However, there is also a significant number of times it has not sold (6), which may indicate that interest can vary.

5. Average Starting Price: The average starting price of 137.98 euros is a good indicator of what buyers are willing to pay on average.

Based on these factors, an estimated maximum purchase price could be between 120 and 160 euros, considering that the condition is 75 and that the average hammer price in the past has been approximately 141.96 euros.

Therefore, a reasonable maximum purchase price could be 150 euros. This allows for a margin to compete in the auction, given the history of hammer prices and the condition of the coin.