Based on the provided data, we can observe that the coin in question has had a starting price in the current auction of 18 euros and is in a conservation grade of 70 (MBC-). Additionally, it has been auctioned in the past on several occasions, with closing prices ranging from 14 to 620 euros.

The average closing price of this coin has been 131.33 euros, with an average starting price of 57.67 euros. Considering that the current conservation grade is 70 (MBC-), we can assume that the estimated purchase price could be in a range similar to the average closing price.

Given that the coin has been auctioned in the past for prices ranging from 14 to 620 euros, and considering its current conservation grade is 70 (MBC-), a maximum estimated purchase price for this coin could be around 150-200 euros. It is important to note that the final price will depend on factors such as demand at the time of the auction and the willingness of buyers to bid on it.