Based on the provided data, we can observe that the coin in question has had a starting price in this auction of 20 euros, with a grade of 30 (BC+). Additionally, it has been auctioned in the past 9 times, being sold on all those occasions.

The average starting price in previous auctions has been 34.8 euros, while the average final price has been 67.11 euros. Regarding the previous prices of this coin, we can see that it has had significant variations in its starting, estimated, and final values throughout previous auctions.

Given that the grade of the coin is 30 (BC+) and considering its good sales history in the past, we could estimate a maximum purchase price around 70-80 euros for this particular auction. It is important to note that the final price may vary depending on the demand at the auction and other factors that may influence buyers' decisions.