Teresa, I'm not sure what thicknesses you are looking for in Styrofoam. I buy mine from Dallas Foam. They have a great prices, selection, ship quickly and have decent shipping costs. I've been looking online for a place to get foam core board at decent prices but no luck so far. I buy mine at Walmart. It's made by Elmer's is 3/16" thick (perfect for cake boards) and 20"x30" for $1.96. Comes in lots of colors but the price higher.
thank you rosemary,i will go on line and look at dallas foam. i am needing 2" thick rounds' a 4" ' 6" and 8"