Based on the data provided, we can observe that the coin in question has had an average starting price of 18.36 euros in previous auctions, with a median closing price of 27.18 euros. The coin's condition has been described as 70 (MBC-), indicating a fairly acceptable preservation.

When analyzing the previous prices of this coin in past auctions, we can see that it has had a fairly wide price range, ranging from 15 euros to 40 euros as a starting price, with estimates ranging from 25 euros to 70 euros. The closing price has fluctuated between 20 euros and 45 euros.

Given that the coin will be auctioned in euros and considering its price history, condition, and demand, as well as the fact that it has sold in most previous auctions, my estimate for the maximum purchase price would be around 40-45 euros. This is based on the previous median closing price and the trend of starting and estimated prices in previous auctions.