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

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. Historical Prices: Looking at previous auction prices, we can see that coins with similar conditions (75) have reached hammer prices of up to 360 euros. However, it should be noted that a condition of 70 is lower than 75, which could justify a lower hammer price.

3. Average Hammer Price: The average hammer price for this coin is 275.73 euros, which gives us a reference for what buyers have been willing to pay in the past.

4. Current Starting Price: The starting price is 40 euros, indicating that the auction house expects moderate interest in the coin.

5. Sales Trends: The coin has been auctioned 12 times, of which it has sold 6 times. This indicates that there is interest in the coin, but also that there is a 50% no-sale rate, which may influence the price.

Based on these factors, an estimated maximum purchase price could be in the range of 200 to 250 euros. This is based on the fact that, although the condition is lower than coins that have reached higher prices, the historical interest and average hammer price suggest that there could be significant value in the coin.

Therefore, a reasonable estimated maximum purchase price could be 250 euros.