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

1. Current Condition: The coin has a condition of 75 (MBC), indicating that it is in quite good shape.

2. Previous Prices: By looking at previous auction prices for coins with a similar condition (75-80), we can see that auction prices have varied. For example:
- In past auctions, coins with a condition of 75 have reached hammer prices of 50, 60, 70, 80, and even 190 euros in exceptional cases.
- The average hammer price for coins with a condition of 75 seems to be in the range of 60-80 euros.

3. Average Hammer Price: The average hammer price for this coin is 84.07 euros, which is also a good indicator of market value.

4. Starting Price: The starting price is 35 euros, suggesting that there is considerable room for the hammer price to be higher.

5. Sales Trends: The coin has been sold in 43 out of 53 auctions, indicating good demand.

Based on these factors, an estimated maximum purchase price could be in the range of 80 to 100 euros, considering that the condition is good and the average hammer price is 84.07 euros. However, to be more conservative and avoid overpaying, a reasonable maximum purchase price could be 90 euros.