Based on the data provided, we can observe that the coin in question has had varying starting and final prices in previous auctions. The current condition of the coin is estimated at 20 (BC-), indicating that it is not in the best condition.

The average starting price in previous auctions has been 73.6 euros, while the average final price has been 96 euros. However, in the last recorded auction, the coin had an estimated starting price of 90 euros and a condition value of 25.

Given that the coin has sold in most of the previous auctions and that the estimated price in the last auction was 110 euros, we could consider a maximum estimated purchase price of around 100-110 euros, taking into account the current condition and previous final prices.

Therefore, my estimate for the maximum purchase price for this coin in the next auction would be around 100-110 euros.