Based on the data provided, we can observe that the coin in question has performed well in previous auctions, with final prices exceeding the estimated price on several occasions. The coin is in excellent condition, with a grade of 100 (S/C).

The average final auction price of the coin in previous auctions has been 21.13 euros, with an average starting price of 10.04 euros. However, in the last auction, the coin reached a final price of 25 euros, surpassing the estimated price of 15 euros.

Given the auction history and the interest this coin has generated in the past, as well as its high grade, we could estimate a maximum purchase price around 30-35 euros. It is important to consider that the final price will depend on the demand at the auction and the willingness of participants to bid on this particular piece.