To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the coin's condition and previous auction prices.

1. Coin Condition: The coin has a condition of 70 (VF-). This indicates that it is in average condition, which generally translates to a lower auction price compared to coins in better condition.

2. Previous Auction Prices: By observing the auction prices of coins with a similar condition (around 70), we can see that the auction prices have varied. For example:
- In previous auctions, coins with a condition of 70 have reached auction prices of 20, 21, 22, 25, and 30 euros.
- The general trend shows that the auction price for coins in VF- condition tends to be in the range of 20 to 30 euros.

3. Average Auction Price: The average auction price for this coin is 67.01 euros, but this includes coins in better condition. Given that the condition of this coin is lower, it is reasonable to adjust our expectations downward.

4. Starting Price: The starting price is 15 euros, which indicates that the auctioneer expects moderate interest in the coin.

5. Final Estimate: Considering all these factors, an estimated maximum purchase price for this coin, taking into account its condition and previous auction prices, could be in the range of 25 to 35 euros. This reflects a price that is reasonable for a coin in VF- condition that has had interest in previous auctions.

Therefore, an estimated maximum purchase price could be 30 euros.