Make your own. I used cardboard cake rounds in various shapes. For the supports underneath, I used foam core cut about 3 " tall and long enough to go across the middle. I put them in an X pattern (making a notch in the middle for the other one to slide into) Secured the legs to the board with glue gun. To stack them - I used straight pins through the legs to the board beneath. I tried glue, but I couldn't get it placed correctly.
I covered my boards in decorative paper before I started and used white foam core. The edges I trimmed with a rick rack that I cut out using my Cricut.