Based on the provided data, the coin has a starting price of 15 euros and has been auctioned once in the past, selling for an average closing price of 30 euros. The coin's condition is 30 (BC+).

Given that the coin sold for 30 euros in the previous auction and considering its good condition, we could estimate a maximum purchase price around 35-40 euros. It is important to consider that the final price will depend on factors such as demand at the time of the auction and buyers' willingness to bid on it.