Based on the provided data, we can observe that the coin has had an average auction closing price of 67.61 euros in previous auctions. Additionally, the current condition of the coin is graded at 30 (BC+).

Considering that the coin has been auctioned 68 times in the past and has been sold 59 times, we can assume that it has a stable demand in the collectors' market.

Given that the current condition of the coin is 30 (BC+), and considering the previous average closing price of 67.61 euros, as well as past auction prices, we could estimate a maximum purchase price around 70-80 euros for this coin in the next auction.

It is important to note that the final auction price may vary depending on factors such as competition from other bidders and specific interest in this coin at the time of the auction.