To estimate a maximum purchase price for the coin in question, we can analyze the provided data:

1. Current Condition: The coin has a condition of 70 (VF-), indicating that it is in relatively good shape.

2. Auction History:
- The average hammer price for coins with a similar condition (70) has been 20 euros on several occasions.
- In previous auctions, hammer prices for coins with a condition of 70 have ranged between 18 and 20 euros.

3. Average Starting and Hammer Price:
- The average starting price is 10.63 euros, and the average hammer price is 23.08 euros. This suggests that, in general, coins tend to sell for a price higher than the starting price.

4. Recent Trends: In the most recent auctions, the hammer price has been 40 euros for a coin with a condition of 30, indicating a growing interest in these coins.

Based on this data, an estimated maximum purchase price for the coin with a condition of 70 could be between 20 and 25 euros, considering that the average hammer price for coins in similar conditions has been around 20 euros and that there is potential for the price to rise a bit more based on demand.

Therefore, a reasonable estimated maximum purchase price could be 25 euros.