Based on the data provided, we can observe that the coin in question has had an average auction closing price of 134.8 euros in previous auctions. Additionally, the condition of this coin is rated at 85 (ebc-).

Considering that the starting price in the upcoming auction is 175 euros and the coin has had an average auction closing price of 134.8 euros in the past, we could estimate a maximum purchase price around 150-160 euros, taking into account the condition and the trend of previous prices.

It is important to note that the final auction price may vary depending on the demand at that specific moment, so it is advisable to monitor the auction's progress to adjust the offer accordingly.