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

1. Current Condition: The coin has a condition of 70 (VF-), which is an acceptable level and may influence its value.

2. Auction History:
- The average hammer price for coins of similar condition (70) has been approximately 26 to 35 euros in previous auctions.
- In past auctions, the highest hammer price for coins in condition 70 was 35 euros.

3. Average Starting and Hammer Price:
- The average starting price is 42.38 euros, and the average hammer price is 70.92 euros. This suggests there is potential for an increase in the hammer price.

4. Recent Trends: In the most recent auction, a coin with a condition of 85 sold for 140 euros, indicating a growing interest in well-preserved coins.

5. Number of Auctions: The coin has been auctioned 15 times, of which 13 have sold, indicating good demand.

Taking all these factors into account, an estimated maximum purchase price for the coin could be between 35 and 50 euros, considering that the highest hammer price for a similar condition was 35 euros and that interest in well-preserved coins is on the rise.

Therefore, a reasonable maximum purchase price could be 45 euros.