On a previous thread about wooly nylon there was a request for cheaper sources for Polyarn. (Polyarn is preferable to wooly nylon since polyester will not melt under a hot iron or in a hot dryer like nylon can.) The best source I have found is R & M Crafts at cigarcityarts.com/polyarn.html. Their price is $4.99 per spool of 1,000 yd. and their shipping rate is less compared to others. I received my order promptly.
Web of Thread (webofthread.com/polyarn) currently has a sale of 20% off of $5.20 per spool but their black and white are out of stock, and their shipping is higher.