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), which indicates that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for similar coins has been 104.15 euros.
- In previous auctions, coins with a similar condition (75) have reached hammer prices of up to 85 euros (in the auction on April 27, 2022) and 90 euros (in the auction on February 2, 2021).

3. Starting Price and Average Starting Price: The current starting price is 50 euros, which is below the average starting price of 66.43 euros. This suggests that there is potential for the hammer price to be higher.

4. Sales Trends: Out of the 15 times it has been auctioned, 13 have resulted in sales, indicating good demand for this coin.

5. Projections Based on Previous Prices: Given that the highest hammer price in the past for a coin of similar condition was 90 euros, and considering the increase in interest and value of coins in the market, an estimated maximum purchase price could be slightly higher.

Taking all these factors into account, an estimated maximum purchase price for this coin could be between 85 and 100 euros. This is based on the auction price history and the current condition of the coin.