Based on the data provided, we can observe that the coin in question has had an average auction price of 639 euros in the past. Additionally, the condition of this coin has been described as '75 (VF).'

When analyzing the previous prices of this coin, we can see that it has had auction prices ranging from 85 euros to 3200 euros, with a maximum estimated price of 1800 euros in one of the auctions.

Given that the condition of the coin is 75 (VF) and considering the previous auction prices as well as the average auction price, we could estimate a maximum purchase price of around 1500 euros for this coin in the upcoming auction. It is important to note that this is just an estimate and the final price may vary depending on various factors in the auction.