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

1. Current Condition: The coin has a condition of 70 (VF-). This indicates that it is in an acceptable state, but not of high quality.

2. Historical Prices: By looking at the auction prices of coins with similar conditions (70-80), we can see that the auction prices have varied. For example:
- In previous auctions, coins with a condition of 70 have reached hammer prices of up to 340 euros.
- Coins with a condition of 80 have reached hammer prices of up to 650 euros.

3. Starting Price and Average Price: The current starting price is 200 euros, and the average hammer price in the past has been 553.17 euros. This suggests that there is potential for an increase in the hammer price.

4. Sales Trends: The coin has been auctioned 125 times, with a high sales percentage (111 out of 125). This indicates a consistent demand.

5. Estimation Based on Previous Prices: Given that the condition is 70, a reasonable hammer price could be in the range of 300 to 400 euros, based on previous price trends for coins of similar condition.

### Final Estimation
Taking all these factors into account, an estimated maximum purchase price for this coin could be between 350 and 400 euros. This would allow for competitive bidding in the auction without exceeding a reasonable limit based on the price history and the current condition of the coin.