Have you checked Walmart or Joannes crafts. I always get mine at both of those placed. Walmart carries the 1/4 sheet, 8", 6" in pkgs. Also Michaels crafts may have them. If you only need a couple, you could go to your local bakery and purchase from them. Amazon and ebay are aso oo choices. Good luck.
Wondering the same. Cannot find round non-corrugated cake boards. Plenty of drums, but no boards/cards.