Based on the data provided, we can observe that the coin in question has had an average auction closing price of 75 euros in previous auctions. Additionally, its current condition is 70 (MBC-).

Considering that the average starting price is 50.48 euros and the coin's condition is relatively good (70), we could estimate a maximum purchase price around 80-90 euros. However, keep in mind that the closing price in previous auctions has reached up to 200 euros, so there could be a significant margin of variation.

In summary, an estimated maximum purchase price for this coin in the upcoming auction could be around 80-90 euros, considering its price history and condition.