Based on the data provided, we can observe that the coin in question has had an average auction price of 76.09 euros in previous auctions. Additionally, its condition has been described as '70 (MBC-)'.

Considering that the coin's condition is quite good (70), and that the average auction price has been 76.09 euros, we could estimate a maximum purchase price around 80-85 euros. Given that the starting price in this auction is 40 euros, it is likely that the final auction price will be above this value, but it is difficult to predict exactly how much.

In summary, an estimated maximum purchase price for this coin in the upcoming auction could be around 80-85 euros, taking into account its previous auction history and its condition.