SASA sells authentic stuff I am pretty certain of that. I used to get my skincare and perfumes from their shops in Asia. The reason they keep prices low is because they are parallel importers for Asia Pacific region.
One of my favorite products is a Japanese stencil for eyebrow trimming which comes in 3 eyebrow shapes. Each is roughly T-shaped with a flat handle at the base. I bought 1 for myself, my sister, and some friends including a make-up artiste who absolutely loves it.
See it here:
http://www.trademe.co.nz/Health-beauty/Hair-care-grooming/Hair-accessories/auction-130038006.htm
Most of the time out of stock in Sasa shops, gotta pre-order them. I don't seem to find it on their online store though.