There are a number of dupes!
Coastal Scents Pro Blending Brush ($4.95)
http://www.coastalscents.com/pro-blending-fluff.html
Sigma E25 ($14 Sigma.com or Amazon)
http://www.sigmabeauty.com/e25-blending/p/E25PARNT
Sedona Lace Universal Blending Brush EB 09 ($13.95)
http://www.sedonalace.com/Cosmetic-Brushes/66/Universal-Blender-EB-09.aspx
Bdellium Tools Maestro Series Blending Brush 776 ($9.68 for studio version @ Amazon $11 for the black Maestro version)
http://bdelliumtools.com/maestro/maestro-776-blending.html
BOOTS No7 Eye Shadow Blend & Contour Brush ($6.99 @ Amazon)
http://www.amazon.com/BOOTS-Shadow-Blend-Contour-Brush/dp/B00IIVI9VK/ref=sr_1_13?ie=UTF8&qid=1433829298&sr=8-13&keywords=Boots+No7+makeup+brushes
Crown Brush C433 Pro Blending Fluff ($14 @ Amazon or $5.49 @ Crown)
http://crownbrush.us/c433-pro-blending-fluff-p-260.html