Based on the provided data, we can observe that the coin in question has had a starting price in the current auction of 15 euros, with a conservation grade of 70 (MBC-). Additionally, it has been auctioned in the past 12 times, with an average starting price of 48.67 euros and an average closing price of 77.5 euros.

Analyzing the previous prices of this coin in past auctions, we can see that it has had a wide price range, from 15 euros to 150 euros. However, the highest estimated price was 225 euros in an auction in 2016.

Given that the current conservation grade of the coin is 70 (MBC-), and considering that in the past an estimated price of 225 euros was reached in an auction, we could estimate a maximum purchase price for this coin at around 200 euros. This is because conservation is an important factor in the valuation of a coin, and although higher prices have been reached in the past, it is important to take into account the current state of the coin.

Therefore, my estimation of the maximum purchase price for this coin in the current auction would be around 200 euros.