To estimate a maximum purchase price for the coin in question, we will consider several factors:

1. Condition of the coin: The coin has a condition rating of 85 (EF-), indicating 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 51.7 euros.
- In previous auctions, coins with a similar condition (85) have reached hammer prices that vary, but there are examples where they have sold for 40 euros (in recent auctions) and up to 65 euros on other occasions.

3. Starting price and estimates:
- The current starting price is 40 euros, and the average starting price in the past has been 36.6 euros.
- The estimated price for this auction is 60 euros, suggesting that there are expectations for the coin to sell at a higher price.

4. Market trends: Since the coin has been auctioned 177 times and has had a good sales percentage (143 out of 177), this indicates a consistent interest in the coin, which may influence a price increase.

Based on these factors, an estimated maximum purchase price for this coin could be between 60 and 80 euros. This is because, although the starting price is 40 euros, the condition and price history suggest it could reach a higher price at auction.

Therefore, a reasonable maximum purchase price could be 70 euros.