Based on the data provided, we can observe that the coin in question has had an average auction closing price of 24.78 euros in previous auctions. Additionally, its condition has been described as '80 (MBC+)'.

Considering the good condition and the average closing price of 24.78 euros, we could estimate a maximum purchase price around 30-35 euros. Given that the estimated price in future auctions has reached up to 50 euros, a maximum purchase price of 35 euros could be a prudent and realistic estimate.