Based on the data provided, we can observe that the coin in question has had a starting price in the current auction of 18 euros, with a grade of 20 (BC-). Additionally, it has been auctioned in the past five times, being sold in three of them.

The average starting price in previous auctions has been 47.6 euros, while the average selling price has been 48.33 euros. Previous prices of this coin have ranged between 25 and 125 euros, with price estimates ranging from 30 to 75 euros.

Given that the current grade of the coin is 20 (BC-) and considering the previous prices and the trend of selling prices, as well as the fact that it will be auctioned in the coming days, we could estimate a maximum purchase price of around 60-70 euros for this coin in the current auction. It is important to note that this is just an estimate and the final price may vary depending on demand and other factors in the auction.