Based on the provided data, we can observe that the coin in question has had an average auction price of 569.18 euros in previous auctions. Additionally, the current condition of the coin is 85 (ebc-).

Considering that the condition is quite good and the average auction price has been 569.18 euros, we could estimate a maximum purchase price around 700-800 euros. Given that the starting price in the upcoming auction is 700 euros, a maximum purchase price of up to 800 euros could be reasonable, especially if there is interest in acquiring the coin.

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