If your health food store does not carry them, they can order them for you. I never had trouble finding daikon, but I always had to order the burdock. I finally ended up planting some in my garden. (I am assuming you mean burdock and not budrock) You can also find burdock growing wild in pastures.
You can buy daikon at Wal-Mart, however, it will not be organic. Most grocery stores carry daikon. Whole Foods might have both. I have also seen burdock at Wild Oats.