Collections Etc. via eBay offers the Solid Microfiber 3-Piece Full Sheet Set
in four colors for $9.97
with free shipping
. That's the lowest total price we could find for a comparable microfiber sheet set by $13. It includes a flat sheet, fitted sheet and two pillowcases.
It's also available in Queen for $10.97, and King for $11.97, both with free shipping. Color options are more limited for these sizes.
Of note, the seller does not specify which color is which in the image supplied.