I was in Jo-Ann's Fabric and Craft store over the weekend and found in the flower/ florist area some colored sand (but the grains are more ballast size) for $2.99 a bag. I bought white and black.. The black makes great coal for the trains.. depending on how deep the car is, either fill with "coal" or a little styrofoam and the coal to save weight, a little elmers-water mix and let try, then spray with some dullcote. For ballast I dyed the white with some black and grey to give it the grey ballast rock look. It came ok, a little too shinny for my liking but might be worth mixing in with some woodland scenic ballast to spread it out farther.