Based on the data provided, we can observe that the coin in question has had a starting price in previous auctions ranging from 4 to 150 euros, with estimated prices ranging from 6 to 225 euros. The final auction price has fluctuated between 1 and 380 euros.

Considering that the current condition of the coin is 85 (ebc-), and that the average final auction price in previous auctions has been 74.83 euros, we could estimate a maximum purchase price around 100-120 euros. Given that the coin will be auctioned in the coming days with a starting price of 25 euros, it is likely that the final auction price will be in a range close to this estimate.

Therefore, an estimated maximum purchase price for this coin in the upcoming auction could be around 100-120 euros.