Based on the data provided, we can observe that the coin in question has had an average auction closing price of 37.33 euros in previous auctions. Additionally, its current condition is 85 (ebc-).

Considering that the starting price this time is 18 euros and the average starting price in previous auctions was 20 euros, we can infer that there is a possibility that the closing price may exceed the current starting price.

Given that the coin has had previous closing prices ranging between 9 and 50 euros, and considering its condition and the upward trend in closing prices, we could estimate a maximum purchase price around 50 euros. However, please note that this is just an estimate and the final price may vary depending on demand at the auction.