Based on the data provided, we can observe that the coin in question has had a starting price in previous auctions ranging from 15 euros to 400 euros. The estimated price has fluctuated between 25 euros and 550 euros, while the final selling price has been between 20 euros and 420 euros. The coin's condition has remained in a range from 30 (BC+) to 95 (FDC).

Given that the current condition of the coin is 30 (BC+), and considering the previous prices of similar auctions, as well as the fact that it has been auctioned 11 times in the past, we could estimate a maximum purchase price around 50-60 euros. It is important to note that this is just an estimate and the final price may vary depending on factors such as demand at the auction and buyers' interest at that specific time.