Buy 10 spools of Dor-Tak 1000m thread in one colour for $11 plus shipping, that is $1.10 per spool what a deal.  Choose your colours from below.  Other sizes available but not in packs, they are just one single spool.

2000m spool $2.75 plus shipping

5000m spool $4.95 plus shipping

The below chart shows you which colours are available in each size.