Based on the data provided, we can observe that the coin in question has had an average auction closing price of 166.91 euros in previous auctions. Additionally, the current condition of the coin is 70 (VF-).

Considering that the condition of the coin is relatively good and the average auction closing price has been 166.91 euros, we could estimate a maximum purchase price around that value or slightly higher, taking into account the upward trend in auction closing prices in previous auctions.

Therefore, an estimated maximum purchase price for this coin in the upcoming auction could be around 170-180 euros, considering the condition and historical closing prices. It is important to note that this is just an estimate and the final price could vary depending on demand and other factors in the auction.