I buy from here:
http://tristan.bc.ca/cart/home.php?cat=38 when there is a door crasher set of 50wt. The door crasher sets change from time to time. I don't remember the shipping being to much for me to not order.
I bought huge cones of Aurifil white, black, gray and cream color some years ago when an online shop went out of business. I didn't know about Aurifil thread then, just knew it was a good buy on thread. LOL It's fun to see new guild members eyes get big when they see the massive cone of Aurifil thread sitting on my thread holder.