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 fairly good shape, but not among the best qualities (FDC).

2. Auction History:
- The average hammer price for similar coins in the past has been 69.5 euros.
- Previous auctions of coins with a similar condition (around 75) have had hammer prices that varied, but some have reached up to 85 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 40 euros, and the average starting price in the past has been 45.16 euros.

4. Recent Trends: In the most recent auctions, hammer prices have shown a trend of being higher, especially for coins in good condition.

Based on these points, an estimated maximum purchase price could be in the range of 80 to 90 euros. This is because, although the average hammer price is 69.5 euros, the condition of the coin and recent trends suggest that it could reach a higher price at auction.

Therefore, a reasonable maximum purchase price could be 85 euros.