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

2. Auction History:
- In the past, the coin has been auctioned 5 times and has sold on all occasions.
- Previous hammer prices for coins with similar conditions (70 and 75) have been 25, 25, 41, and 45 euros.
- The average hammer price for the previous auctions is approximately 33 euros.

3. Starting Price and Average Hammer Price:
- The current starting price is 25 euros, which is slightly lower than the average hammer price of previous auctions.
- The average hammer price of 32.2 euros suggests that there is interest in this coin.

4. Price Trends:
- The trend of hammer prices seems to be in a range of 25 to 45 euros for similar conditions.

Based on these factors, an estimated maximum purchase price could be in the range of 40 to 50 euros, considering that the condition is good and there has been interest in the past. However, since the starting price is 25 euros, it is likely that the hammer price will not significantly exceed the previous average hammer price.

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