Instead of running it once per day, you could run it hourly. Rank the items with the same algorithm, but take into account time left on the auction. An item exp

Instead of running it once per day, you could run it hourly. Rank the items with the same algorithm, but take into account time left on the auction. An item expiring soon that scores really high could be purchased early so it doesn't get away. Items expiring later could be watched and dumped if the price goes too high, or determined to be worth the extra expense, if the amount is available in savings, so the more expensive good items don't get away either.