ECS has decent prices for DMC floss, and they are good about listing out-of-stock colors. And the shipping prices are reasonable, too. I also buy from a competing site that sells the Zweigart linen I like, and for a couple of skeins, from my local needlepoint shop.
If you are buying 44 colors, you'll get a good price online even with the shipping. Look for a place that sells it for about 50 cents/skein or less and charges postage based on weight.