Based on the data provided, we can observe that the coin in question has had an average auction closing price of 81.38 euros in previous auctions. Additionally, its condition has been described as "70 (MBC-)", indicating that it is in fairly good condition.

Considering that the starting price for the next auction is 25 euros and the historical average starting price has been 40 euros, we could estimate that the closing price might fall within a similar range to the previous average closing price, around 81.38 euros.

Given that the coin's condition is 70 (MBC-), which is good, and considering the history of previous closing prices as well as the interest in the coin (auctioned 20 times in the past), we could estimate a maximum purchase price around 85-90 euros. This range takes into account the quality of the condition, demand for the coin, and previous closing prices.

It's important to note that the final closing price may vary depending on factors such as competition in the auction, buyer interest, and other elements that could influence the final bid.