Based on the provided data, we can observe that the coin in question has had a starting price in previous auctions ranging from 18 to 90 euros, with estimated prices ranging from 30 to 150 euros. The final auction price has fluctuated between 25 and 115 euros.

The conservation grade of the coin to be auctioned is 30 (BC+), indicating that it is in an acceptable but not excellent condition.

Given that the average final auction price in previous auctions has been 63.75 euros and the average starting price has been 52.63 euros, we can estimate that the price of this coin in the upcoming auction could be around those values.

Taking into account the coin's conservation and previous prices, as well as the fact that it has sold in most previous auctions, we could estimate a maximum purchase price in the range of 60 to 70 euros. However, keep in mind that the final price will depend on the demand at the auction and other factors that may influence the bidding.