Based on the provided data, the coin in question has a conservation grade of 75 (MBC) and has had a consistent starting price of 25 euros in previous auctions, with a hammer price also of 25 euros. This indicates that, despite the estimated price being 40 euros, there has been no increase in the hammer price in past auctions.

Since the coin has been auctioned twice and has reached the same hammer price on both occasions, it is reasonable to assume that interest in this coin has not increased significantly. Furthermore, the fact that it will be auctioned again shortly suggests that the market has not changed drastically.

Therefore, a maximum estimated purchase price could be slightly higher than the previous hammer price, but not by much, given that interest seems to be stable. An estimated maximum purchase price could be around 30-35 euros, considering a small margin for competition in the auction.