Yes. They do around significant holidays throughout the year. It is periodic, but if you subscribe to their mail list you'll get emails when they are having some form of a sale. Also if you check the forums on Adisc regularly someone usually posts if they are having a sale.
Maybe one specific Post section for sales on diapers, disp or cloth, along with US or Canada and the website address? Could be very helpful instead of surfing and searching all the time?