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 70 (VF-), which indicates that it is in relatively good shape, but not of the highest quality (UNC).

2. Auction History:
- The average hammer price in previous auctions is 84.11 euros.
- The coin has been auctioned 12 times, of which it has sold 10 times, indicating good demand.
- Previous hammer prices for coins with similar conditions (75 and 80) have ranged between 60 and 200 euros.

3. Starting Price and Estimates:
- The current starting price is 40 euros, which is relatively low compared to the average hammer price.
- The estimated price for this auction is 90 euros, suggesting expectations for it to sell at a higher price.

4. Price Trends:
- In previous auctions, hammer prices have varied, but there are examples of coins with similar conditions that have sold for significantly higher prices (up to 200 euros).

Based on these factors, an estimated maximum purchase price could be in the range of 80 to 100 euros. This is because, although the condition is not the highest, demand and price history suggest it could reach a higher price at auction.

Therefore, a reasonable maximum purchase price could be 90 euros.