Based on the provided data, we can see that the coin in question has a conservation grade of 70 (MBC-), with a starting price in the current auction of 15 euros. Additionally, it has been auctioned three times in the past, selling on all those occasions. The average starting price in previous auctions was 20 euros, while the average final price was 48.67 euros.

Furthermore, we have information on two previous auctions of this same coin:

1. In the auction on July 3, 2014, the coin had a starting price of 25 euros, an estimated price of 40 euros, and was sold for 51 euros. Conservation information is not provided in this case.

2. In the auction on February 2, 2021, the coin did not have a specified starting price, but was estimated at 60 euros and sold for 65 euros. In this case, the conservation grade of the coin was 80.

Given that the coin has sold in all previous auctions and considering the price trends, as well as the current conservation grade of 70 (MBC-), we could estimate a maximum purchase price around 55-60 euros. It is important to note that this is just an estimate and the final price in the current auction may vary depending on demand and other factors.