Based on the data provided, we can observe that the coin in question has had an average auction closing price of 152.91 euros in previous auctions. Additionally, the current condition of the coin is graded at 70 (VF-).

Considering that the current condition of the coin is 70 and that the average auction closing price in previous auctions has been 152.91 euros, we can estimate a maximum purchase price for this coin in the upcoming auction.

Given that the coin's condition is 70 (VF-), and considering that the condition scale goes up to 110 (FDC), we could consider a maximum purchase price slightly below the average auction closing price in previous auctions.

Therefore, an estimated maximum purchase price for this coin in the upcoming auction could be around 140-150 euros. It is important to note that this is just an estimate and the final auction price may vary depending on various factors such as demand at that specific time.