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-), indicating that it is in an acceptable state, but not among the best qualities. This may influence the price, as coins in better condition tend to reach higher prices.

2. Current Starting Price and Previous Prices: The current starting price is 1400 euros. In previous auctions, the average hammer price has been 1303.11 euros, suggesting that buyers are willing to pay close to this value on average.

3. Price Trends: By observing previous hammer prices for coins with similar conditions (70 and 75), we can see that they have reached hammer prices of up to 1400 euros on some occasions. However, the highest recorded hammer price for a condition of 70 was 1330 euros.

4. Auction Expectations: Given that a coin with a condition of 70 will be auctioned and considering the starting price of 1400 euros, it is reasonable to assume that buyers might be willing to pay a little more than the previous average hammer price, but not much more, since the condition is not the highest.

Based on these factors, an estimated maximum purchase price could be around 1400-1500 euros, considering that the starting price is 1400 euros and there is interest in the coin, but also taking into account that the condition limits the potential for a significantly higher hammer price.

Therefore, a reasonable maximum purchase price could be 1500 euros.