Based on the provided data, we can observe that the coin in question has had quite variable final prices in previous auctions, ranging from 9 euros to 3200 euros. The average final auction price from previous auctions is 432.33 euros.

The current condition of the coin is rated at 25 (BC), indicating that it is not in the best condition, but also not the worst.

Given that the coin will be auctioned in the upcoming days with a starting price of 18 euros, and considering the average final auction price from previous auctions is 432.33 euros, we could estimate a maximum purchase price around 450 euros.

It is important to consider that the final auction price will depend on various factors, such as the interest of present buyers, competition in the auction, and the condition of the coin compared to previous auctions.