Hello,
The ones that are priced at $2.50 are Weeks Dye Works Thread and they are an over dyed floss. To the right of the picture of the pattern, right above the price, you should see the details listed for this design. Such as the Stitch Count, the fabric used and what brands of floss are used. Then in the Supply box below, we list the all of the supplies so you can choose to purchase them with the pattern. Also, if you click on the "Description" tab, which is located underneath the picture of the pattern as well, you will find more details and even the DMC alternates that can be used in place of the Weeks Dye Works Thread. Hope this information helps :)
~Kristi @ ECS