Based on the data provided, we can observe that the coin in question had an opening price in the current auction of 18 euros, with a conservation grade of 70 (MBC-). Additionally, it has been auctioned in the past on several occasions, with varying starting and final prices over the years.

The average starting price of previous auctions has been 30.75 euros, while the average final price has been 46.4 euros. The coin has been sold in 85.7% of previous auctions.

Based on the previous prices of the coin, we can see that it has had a wide price range, with estimates ranging from 30 euros to 90 euros. The conservation grade of the coin has varied in previous auctions, with values ranging from 30 to 80.

Given that the coin is in a conservation grade of 70 (MBC-), and considering the previous prices and trends of previous auctions, my estimate for the maximum purchase price of this coin would be around 60-70 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.