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), which indicates that it is in fairly good shape, but not the best possible condition.

2. Auction History:
- The average hammer price in previous auctions is 100.63 euros.
- In past auctions, the hammer price has varied, with a maximum of 220 euros in 2018 for a coin with a condition of 85.
- The last auction in 2022 had a hammer price of 75 euros, indicating that interest may have fluctuated.

3. Starting Price and Average Starting Price:
- The current starting price is 50 euros, and the average starting price in the past has been 55.63 euros.

4. Sales Trends: The coin has sold every time it has been auctioned, suggesting consistent interest.

Given that the coin's condition is 75 and considering the auction price history, an estimated maximum purchase price could be in a range between the average hammer price and the highest recorded price.

Taking all these factors into account, an estimated maximum purchase price could be approximately 120 euros. This is based on the fact that, although the condition is not the highest, interest in the coin has been consistent and the hammer price has reached higher figures in the past.