I cant seam to find a cake board that is durable enough to withhold a heavy cake. All I can find is the cardboard ones from wal- mart and hobby lobby
I had the same problem here in NC. What I ended up doing is going to the local Dollar store and buying a foam core board. I measure and cut to the size I need and typically will double it. I tape it all together and then cover with pretty wrapping paper or fondant etc. It's inexpensive and sturdy. I used this method recently on a 3 tier wedding cake and had no issues with it at all.
I second WillosCry, I also made my own sturdy boards out of the foam core board (Elmers Brand) I doubled it and glued it (non-toxic glue). I've either lined it with wax paper and put a nice ribbon border so you don't see the ugly edges or you can wrap it with foil or fondant. They are relatively easy to find and any craft store or even walmart .