@Crystal, I order them all from Amazon! Free shipping! These are the masonite boards I use:
Since they can be reused, I only use them with cakes for clients who I know will return them. Otherwise I double up on the cardboard cake boards (also ordered from Amazon) or cut my own foam boards I buy at Wal-Mart.
A few days ago I splurged and ordered two 1/2 cake drums from Global Sugar Art for a few wedding cakes coming in June, since Amazon didn’t have the specific ones I wanted. $16 for the cake boards, $35 for the shipping ~ which I had a hard time swallowing, but I sucked it up and ordered them anyway. But then yesterday I got an email from them saying they were adding an additional $15 to my shipping charges, bringing the shipping total up to $50!!! Yikes! For a $16 order, really??! So I canceled that order, I’ll have to figure something else out. One of the hazards of living on this island I guess :)