Based on the provided data, we can observe that the coin in question had a starting price of 18 euros in this auction, with a conservation grade of 30 (BC+). Additionally, it has been auctioned in the past seven times, being sold in all of them. The average starting price in previous auctions has been 30.57 euros, while the average final price has been 52 euros.

Regarding the previous prices of this coin, we can see that it has had different starting, estimated, and final values in previous auctions, with conservation grades ranging from 30 to 75.

Given that the coin has sold in all previous auctions and its conservation is relatively good (30 - BC+), we could estimate a maximum purchase price around the average final price of previous auctions, approximately 52 euros. However, keep in mind that this is just an estimate and the final price could vary depending on the demand in the current auction.