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 (VF-). This is an important factor, as coins in better condition tend to reach higher prices.

2. Current Listing Price and Previous Prices: The current listing price is 600 euros. In previous auctions, we have seen hammer prices that vary significantly depending on the condition. For example:
- In 2020, a coin with a condition of 25 sold for 850 euros.
- In 2019, a coin with a condition of 80 sold for 1900 euros.
- In 2018, coins with conditions of 85 and 90 sold for 1600 and 3800 euros, respectively.

3. Average Hammer Price: The average hammer price for this coin is 1797.5 euros, indicating that, in general, coins of this reference tend to sell for higher prices.

4. Auction Trends: The coin has been auctioned 42 times, of which 34 have sold. This suggests there is a consistent interest in this coin.

5. Condition Comparison: Since the condition of 70 is lower than the conditions of 80 and 90 that have reached higher hammer prices, it is reasonable to adjust the estimated price downward.

Taking all these factors into account, an estimated maximum purchase price for this coin could be between 1000 and 1300 euros. This is based on the fact that, although the condition is not the highest, the interest in the coin and the average hammer price suggest it could reach a significant price at auction.