Based on the provided data, we can observe that the coin has had starting prices ranging from 1 euro to 250 euros, with estimated prices ranging from 6 euros to 400 euros. The final auction price has fluctuated between 6 euros and 320 euros.

Given that the condition of the coin to be auctioned is 30 (BC+), and considering the previous prices of similar auctions as well as the average final auction price of 47.9 euros, we can estimate a maximum purchase price for this coin at around 50-60 euros.

It is important to note that the final auction price may vary depending on factors such as demand at the time of the auction and the willingness of buyers to bid on the coin.