Based on the data provided, we can observe that the coin in question has had an average auction closing price of 125.13 euros in previous auctions. Additionally, its condition has been described as '80 (MBC+)'.

Considering that the coin's condition is quite good and the average auction closing price has been 125.13 euros, we could estimate a maximum purchase price around 140-150 euros. Since the coin will be auctioned in the coming days, it is possible that the closing price may be slightly higher due to demand at the auction.

Therefore, my estimate for the maximum purchase price for this coin in the upcoming auction would be around 140-150 euros.