Based on the data provided, we can observe that the coin has had an average auction closing price of 33.3 euros in previous auctions. Additionally, the current condition of the coin is 100 (UNC), indicating that it is in excellent condition.

Considering that the starting price for the upcoming auction is 20 euros and the average starting price in previous auctions was 19.38 euros, we can estimate that the closing price could exceed 33.3 euros.

Given that the coin has had previous closing prices ranging from 1 euro to 110 euros, and that the estimated price in previous auctions has reached up to 200 euros, we could consider a maximum estimated purchase price of around 150 euros for this coin in the upcoming auction, taking into account its condition and the history of previous prices.