Based on the provided data, we can observe that the coin in question has had an average auction closing price of 27.35 euros in previous auctions. Additionally, the condition of the coin on this occasion is 80 (VF+).

Considering that the condition of the coin is good but not excellent, and taking into account the previous average closing price, as well as the current starting price of 12 euros, we could estimate a maximum purchase price around 30-35 euros.

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.