As a knitter, I have a yarn stash like you wouldn't believe (unless you're a knitter too).

I've taken a picture that I'll show you in case you don't believe me, but I have a wardrobe cabinet filled with skeins of yarn in a variety of colors, that I use for my business of making handmade doll clothes and handmade bear clothes.

I have a couple of Squidoo lenses dealing with my passion for knitting:  Instarsia Knitting and Knitting for Knit Wits.

My preferred yarn to work with is Red Heart Super Saver brand yarn.  It is a worsted weight yarn that comes in a large variety of colors, and keeps it color VERY well with wear.  I have sold several sweaters used for dogs, and they get washed frequently, and the dog owners have reported to me how surprised they were to have the colors remain as vibrant as the day they bought the sweater.

Red Heart yarn is produced by Coats & Clark.  It comes in a variety of lines of various textures, thicknesses, and softness levels.  I usually buy yarn locally from Wal Mart or Hobby Lobby as I need a particular color.  Occassionally I will check out eBay for lots of common colors as even with shipping, I can sometimes get a better price per skein that way.  I've included a link to current listings available on eBay - its a great way to shop for yarn, especially if you don't have a craft store available locally, or the ones that you do have charge a lot per skein.

I've done very limited work with more speciality  yarns, I really like working with this brand of yarn because its durable, vibrant, and gives me a great color pallatte to work with for my buyers.
One great place to purchase your yarn is Joann.com - they are a broad selection of yarn brands, including Red Heart. You can visit their website by clicking one of the logos below, and check out their current promotions and sale items