To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Current Condition: The coin has a condition of 70 (VF-). This is an important factor, as coins in better condition tend to reach higher prices.

2. Auction History:
- The average hammer price for coins with a similar condition (70) in the past has been approximately 110 euros (for example, in the auction on 2020-12-16).
- In other auctions, coins with a condition of 80 have reached hammer prices of up to 240 euros, indicating that there is a market willing to pay more for coins in better condition.

3. Starting Price and Average Starting Price:
- The current starting price is 60 euros, which is below the average starting price of 100.39 euros. This suggests that the starting price is attractive and could attract more bidders.

4. Sales Trends: The coin has been sold in 18 of the 21 previous auctions, indicating good demand.

5. Price Estimation:
- Given that the average hammer price for coins with a condition of 70 has been 110 euros and considering that the starting price is 60 euros, an estimated maximum purchase price could be between 110 and 150 euros, depending on the competition in the auction.

Taking all these factors into account, an estimated maximum purchase price for this coin could be 120 euros. This allows for a margin for competition and aligns with historical hammer prices for coins of similar condition.