Based on the data provided, we can observe that the coin in question has had a considerable variation in auction closing prices in previous auctions. The current starting price is 25 euros, and the coin's condition is estimated at 70 (VF-).

Taking into account the previous auction closing prices and the coin's condition, as well as the fact that it has been auctioned 155 times in the past, we can estimate a maximum purchase price for this coin in the upcoming auction.

Given that the average auction closing price in previous auctions has been 99.6 euros, and considering the current condition of the coin, we could estimate a maximum purchase price around 110 euros. However, please note that this is just an estimate and the final price could vary depending on the demand at the auction.

In summary, an estimated maximum purchase price for this coin in the upcoming auction could be around 110 euros.