Craftsy has a sale now but they are almost gone last time I checked. $8 for the large spool of 1422 yards. $3 for the small spool.
I bought enough Aurufil to last me for years at Tristan when they had the doorbuster specials. The best price I have ever seen then or since on Aurifil. The mako cotton thread sold at Tristan now is the same thread as Aurifil. Both made in Italy. If you need 80wt black Aurifil 17,000m cone for $15 check this out:
http://www.tristan.bc.ca/cart/produc...1&cat=7&page=2
I got many different colored huge cones (the size you see many holding for ads) of 50wt for under $20 each several years ago when they were being clearanced out.