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 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 in the past has been 69.25 euros.
- Previous hammer prices for coins with similar conditions (75) have ranged from 43 to 80 euros, with a notable hammer price of 750 euros in a previous auction, although that may be an exceptional case.

3. Starting Price and Average Starting Price:
- The current starting price is 40 euros, which is slightly lower than the average starting price of 43.78 euros. This could indicate that there is a buying opportunity at a reasonable price.

4. Recent Trends: In the most recent auctions, hammer prices have been in the range of 50 to 80 euros for similar conditions.

Based on these factors, an estimated maximum purchase price could be in the range of 70 to 90 euros. This is based on the average hammer price and the condition of the coin. Therefore, a reasonable maximum purchase price could be 80 euros.