I try to keep a variety of rayon and polyester colors. I try to keep a light, medium and dark of each main color I use and you can't go wrong with extra blues and greens. The thread websites themselves offer sales but I've had good luck on eBay especially for larger cones, prices are great. You can search the particulars of what you're looking for as "nylon blue embroidery thread" or "poly yellow embroidery thread" to narrow your search. Usually for most sites, the more you order, the cheaper the S/H is. A sweet addiction it is!!