Based on the provided data, we can observe that the coin in question has had a starting price of 30 euros in this auction and is in a conservation grade of 30 (BC+). Additionally, it has been auctioned in the past five times, all of which resulted in a sale.

The average starting price in previous auctions has been 46 euros, while the average final price has been 77 euros. In previous auctions, final prices have ranged between 60 and 85 euros, with a conservation grade of 75 in one of the auctions.

Given that the coin is in a conservation grade of 30 (BC+), and considering the previous final prices, as well as the current starting price, we could estimate a maximum purchase price around 80-85 euros. It is important to note that this is just an estimate and the final price may vary depending on demand in the current auction.