Based on the data provided, we can observe that the coin in question has had an average auction price of 25.06 euros in previous auctions. Additionally, its condition has been described as '80 (MBC+)'.

Considering that the condition is quite good (80), and that the average auction price has been 25.06 euros, we could estimate a maximum purchase price around that value or slightly higher, taking into account that the coin is in a favorable condition.

Therefore, an estimated maximum purchase price for this coin in the next auction could be around 26 to 28 euros, considering the trend of previous prices and the quality of the coin's condition.