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

1. Coin Condition: The coin has a condition of 70 (VF-), indicating that it is in an acceptable state, but not of the highest quality.

2. Previous Auction Prices:
- The average hammer price for similar coins has been 165.94 euros.
- In previous auctions, coins with a similar condition (70) have had hammer prices that varied, but some examples are:
- 80 euros in 2020 (condition 80).
- 25 euros in 2018 (condition 70).
- 40 euros in 2022 (condition 70).

3. Starting Prices and Estimated Prices:
- The current starting price is 30 euros, and the average starting price in the past has been 57.62 euros.
- The estimated price for this auction is 50 euros.

4. Sales Trends: The coin has been auctioned 70 times, of which it has sold 67 times, indicating a high sales rate.

Based on these factors, a reasonable maximum purchase price could be in the range of 80 to 120 euros, considering that the average hammer price is significantly higher than the starting price and that the condition is acceptable.

Therefore, an estimated maximum purchase price could be 100 euros. This allows for competition in the auction and aligns with previous hammer prices for coins of similar condition.