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

1. Current Condition: The coin has a condition of 70 (VF-). This indicates that it is in relatively good shape, but not of the highest quality (UNC).

2. Previous Auction Prices: By looking at the auction prices of coins with similar conditions (around 70), we can see that:
- In the auction on 2022-09-20, a coin with a condition of 70 was auctioned at a price that is not specified, but was estimated at 25 euros.
- In the auction on 2022-02-22, a coin with a condition of 75 was auctioned for 35 euros.
- In the auction on 2022-07-07, a coin with a condition of 75 was auctioned for 35 euros.

3. Price Trends: The average auction price for this coin is 54.18 euros, suggesting that, in general, coins of this reference tend to reach higher prices at auctions.

4. Starting Price: The starting price is 15 euros, indicating that the seller expects a lower price initially, but this does not necessarily reflect the actual value of the coin.

5. Estimation: Given that the condition of the coin is 70 and considering the previous auction prices, an estimated maximum purchase price could be between 35 and 50 euros, taking into account that the coin could reach a higher price if there is interest in the auction.

Therefore, an estimated maximum purchase price for this coin could be 45 euros.