Based on the data provided, we can observe that the coin in question has had an average auction closing price of 139.91 euros in previous auctions. Additionally, the current condition of the coin is 80 (MBC+).

Considering that the coin will be auctioned in the coming days with a starting price of 75 euros and has had an average closing price of 139.91 euros in the past, we can estimate a maximum purchase price based on this data.

Given that the condition of the coin is 80 (MBC+), and considering that previous auctions have had closing prices higher than the current starting price, we could consider an estimated maximum purchase price around 150-160 euros.

It is important to note that the final auction price will depend on several factors, such as demand at that specific time, competition from other bidders, and interest in the particular coin.