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 (VF), indicating that it is in acceptable shape, but not of the highest quality.

2. Auction History:
- The average hammer price in previous auctions is 82.61 euros.
- The average starting price is 68.39 euros.
- In past auctions, we have seen hammer prices that varied significantly, ranging from 3 euros to 200 euros, depending on the condition and demand at that time.

3. Recent Auction Prices:
- In the most recent auction, the hammer price was 55 euros for a coin with a condition of 80.
- In another recent auction, the hammer price was 70 euros for a coin with a condition of 90.

4. Price Trends:
- The general trend seems to be that coins in a condition similar to the current one (75) have had hammer prices ranging between 50 and 80 euros in recent auctions.

Based on this data, an estimated maximum purchase price for the coin in condition 75 could be in the range of 70 to 90 euros, considering that the starting price is 40 euros and that interest in the coin may influence the final price.

Therefore, a reasonable estimated maximum purchase price could be 80 euros.