Based on the data provided, we can observe that the coin has had an average auction closing price of 152.01 euros in previous auctions. Additionally, the condition of this coin is rated at 75 (MBC).

Considering that the starting price in the upcoming auction is 175 euros and the coin has had an average auction closing price of 152.01 euros in the past, we could estimate a maximum purchase price around that value. However, taking into account that the condition of the coin is 75 (MBC), we could slightly adjust that price downwards.

Therefore, an estimated maximum purchase price for this coin in the upcoming auction could be around 145-150 euros. It is important to note that this is just an estimate and the final price could vary depending on the demand at the auction and other factors.