Based on the data provided, we can observe that the coin in question has had an average auction closing price of 83.25 euros in previous auctions. Additionally, it has been auctioned four times in the past, and has been sold in all of them.

Considering that the coin's condition is 30 (BC+), and taking into account the previous auction prices where the estimated price has ranged between 40 and 125 euros, we could estimate a maximum purchase price for this coin in the upcoming auction.

Given that the average auction closing price has been 83.25 euros and the highest estimated price in previous auctions was 125 euros, we could suggest a maximum purchase price around 120 euros, considering the condition and price history of this coin in previous auctions.