Yeah, I'm not one to trust fasttech though.. and all my local dealers have good prices on Kanger products.
I'd rather be safe and order authentic.
I hear you.
My First 2 Subtanks were Authentic Kanger's. I then bought 2 of the above FT Clones as Back Ups and for Parts.
Have to say, for clones, they Aren't Bad at all.
And I now have 2 of these coming to Convert my Authentic Subtanks to Top Fill's.

$4.22 Replacement Tank Set for SUBTANK Mini Clearomizer - stainless steel + glass at FastTech - Worldwide Free Shipping