Based on the data provided, we can observe that the coin in question has had an average auction closing price of 28.86 euros in previous auctions. Additionally, its current condition is estimated at 70 (VF+), indicating that it is not in the best condition, but also not in the worst.

Taking into account the coin's previous auction prices and its current condition, we can estimate a maximum purchase price for this coin in the upcoming auction. Given that the average closing price has been 28.86 euros and the current condition is 70 (VF+), we could consider an estimated 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 pay attention to the auction and adjust the offer accordingly.