These are a few websites and vendors that I have done business with, and I appreciate enough about them to give "an enthusiastic two thumbs up!"  These are listed in no special order-

Article Pract Article Pract is one of my favorite local yarn stores.  Great Selection.  It is my "fix" when I just NEED to buy yarn. I love the owner Christina, and the staff is top drawer.  Artfibers Fine Yarns This store... this vendor... this place.... If you ever get a chance to visit their store- dont pass it up. Some of the worlds most amazing yarns.  Rox is the owner-  Wonderful gal.  the store is like coming home.  At first glance, you think the yarn is very expensive.  But when you see what you get per yard, it is very fair traded.  The yarn is on cones- so you have lots of yardage (which means less ends to weave) and no knots!!!  Knitterly This store was an accidental find-  but WHAT a find.  Again, great selection, great location, wonderful staff.  Its worth the drive! Smiley's Yarn GREAT place for sale stock n stash yarn.  Quick Shipping, friendly... I only visit as an online store, they are out of my area. Elann.com A good place for yarn.  Great prices, good selection.  It's only an online store.  They are good to do business with, and quick shipping.  Never a disappointment. WEBS yarn Vast Selection- quick shipping Halcyon Yarn I think this place sells everything fiber related.  They are great to deal with!