Based on the provided data, we can observe that the coin in question has had a starting price of 15 euros in this auction, with a conservation grade of 30 (BC+). Additionally, it has been auctioned in the past on several occasions, with varying starting and final prices.

The average starting price of this coin in previous auctions has been 42.5 euros, while the average final price has been 57.67 euros. In previous auctions, estimated prices have ranged between 40 and 150 euros.

Given that the conservation grade of the coin is 30 (BC+), and considering the previous prices of similar auctions, as well as the current starting price, we could estimate a maximum purchase price around 60-70 euros. It is important to note that this is just an estimate and the final price may vary depending on the demand in the current auction.