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

1. Current Condition: The coin has a condition of 70 (MBC-), which indicates that it is in relatively good shape. This suggests that its price could be in the upper range of previous auctions.

2. Previous Prices: By observing the hammer prices from previous auctions for coins with similar conditions (70 and 75), we can see that the hammer prices have varied. For example:
- In previous auctions, coins with a condition of 70 have reached hammer prices of up to 75 euros.
- The coin with a condition of 75 has reached hammer prices of up to 95 euros.

3. Average Hammer Price: The average hammer price for this coin is 71.95 euros, which can also serve as a reference.

4. Starting Price: The starting price is 40 euros, indicating that the auctioneer expects interest in the coin.

5. Sales Trends: The coin has been sold in 68 out of 81 auctions, indicating good demand.

Based on these factors, an estimated maximum purchase price could be between 75 and 90 euros, considering that the condition is 70 and there are precedents for hammer prices in that range.

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