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

1. Current Condition: The coin has a condition of 70 (VF-), indicating that it is in relatively good shape, but not among the highest qualities.

2. Auction History:
- The average hammer price in previous auctions is 39.33 euros.
- In past auctions, hammer prices have varied, with a maximum of 100 euros in 2017 and a minimum of 12 euros in 2014.
- The last auction where a coin with a similar condition (70) was sold had a price of 50 euros.

3. Starting Price and Estimates:
- The current starting price is 25 euros, which is slightly higher than the average starting price of 21.75 euros in previous auctions.
- The estimated hammer price for this auction has not been provided, but based on the history, it could be in a similar range to the average hammer price.

4. Price Trends:
- Given that the coin has been sold on all previous occasions and considering that the condition is 70, it is reasonable to assume that interest in this coin will remain.

Based on these factors, an estimated maximum purchase price could be in the range of 50 to 70 euros, considering that the condition is good and that the price history shows that similar coins have reached hammer prices in that range.

Therefore, a reasonable maximum purchase price could be 65 euros.