Based on the data provided, we can observe that the coin in question has had a starting price in this auction of 12 euros, with a conservation grade of 30 (BC+). Additionally, it has been auctioned in the past six times, with an average starting price of 82.8 euros and an average closing price of 160.67 euros.

When analyzing the previous prices of this coin, we can see that it has had a fairly wide price range, from 12 euros up to 200 euros as a starting price. The estimated maximum purchase price in previous auctions has been 300 euros, with a maximum closing price of 440 euros.

Given that the current conservation grade of the coin is 30 (BC+), and considering the previous prices and the average closing price, as well as the fact that it has been auctioned six times in the past, we could estimate a maximum purchase price in this auction around 250-300 euros. It is important to note that the final price may vary depending on the demand at the auction and other external factors.