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 suggests that its value should be above that of coins in worse conditions.

2. Auction History:
- The average hammer price in previous auctions is 171 euros, indicating that, in general, coins of this reference tend to sell for significantly higher prices than the starting price.
- The last auction with a similar condition (75) had a hammer price of 42 euros, which may indicate that interest in this particular coin is moderate.

3. Starting Price and Average Starting Price:
- The current starting price is 40 euros, which is below the average starting price of 62 euros. This could indicate that there is a buying opportunity at a relatively low price.

4. Price Trends:
- In previous auctions, hammer prices have varied considerably, ranging from 41 euros to 850 euros, depending on the condition and market interest at that time.

Based on these factors, an estimated maximum purchase price could be set in a range that considers both the average hammer price and the current condition. Given that the average hammer price is 171 euros and considering that the condition is good but not excellent, a reasonable maximum purchase price could be:

Estimated maximum purchase price: 150 euros.

This price reflects a balance between market interest, the condition of the coin, and the price history in previous auctions.