If you start by buying an assortment of spheres, you can fill in whatever sells best by buying these best sellers by the casepack.
OR Make your own assortment by purchasing casepacks
OR Buy spheres by the case to add another color or size to an assortment
3" spheres come in packs of 12 of a color.
4.5" spheres come in packs of 8 of a color.
6" spheres come in packs of 6 of a color.