Based on the provided data, we can observe that the coin in question had an opening price of 15 euros in the current auction, with a conservation grade of 70 (MBC-). Additionally, it has been auctioned in the past 23 times, sold in 22 instances, and remained unsold once.

The average opening price of previous auctions has been 49.57 euros, while the average closing price has been 78.32 euros. Conservation grades in previous auctions have ranged from 70 to 85.

Analyzing the coin's past prices, we can see that it has had a wide range of estimated opening, closing, and final values over the years. The highest recorded closing price was 260 euros.

Given that the coin is in a conservation grade of 70 (MBC-) and considering the previous closing prices as well as the average closing price, we could estimate a maximum purchase price of around 100-120 euros for this coin in the current 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.