The K-cups occasionally go on sale, but no one knows when. Check the Best Buy "Deal of the Day" on their website every day. The deals reset at midnight Central Time, and last for only 24 hours (or until supplies run out).
That last bit is important - for the best selection, you need to shop the "Deals of the Day" when they are first posted (1AM Eastern, 12 Midnight Central, 11 PM Mountain, 10 PM Pacific). If you wait until 6 or 7 PM, your preferred K-cup may be out of stock, with only the more undesirable brands available for purchase. Pumpkin spice coffee ? Ewwwww !