Based on the data provided, we can observe that the coin in question has had an average auction closing price of 25.27 euros in previous auctions. Additionally, the condition of this coin has been described as '70 (MBC-)'.

Considering that the condition of the coin is good but not excellent, and that the average closing price has been 25.27 euros, we could estimate a maximum purchase price around 30-35 euros. This is because, although there have been auctions above this range, the majority of closing prices have been around 25 euros.

Therefore, an estimated maximum purchase price for this coin in the next auction could be around 30-35 euros.