You should have him stock some JOYE e-cigs, straight from the manufacturer. Cheaper in bulk and JOYE is also the manufacturer of Janty's stuff.
He wobbled one hand in a so-so motion. I asked what the problem was. He said some buyers complained that these didn't draw like a cigarette at all, and they wouldn't use them. He'd seen his share of unhappy buyers. Ooops.
He still isn't stocking any other e-cigs, despite my advice. Like most such owners, he does not want returns and failures and unhappy customers.
He and I both settled on the idea of ONLY A TRUE DISPOSABLE. That's the way to find out if e-smoking is something an ex-smoker wants to sink a real investment in.
Try a Ruyan Jazz, move on to the more fussy refillable, rechargeable e-cigs. I gave him Web pages and phone numbers of several reliable suppliers and e-cigs he could stock (I never expect e-liquid to be stocked in any brick-and-mortar shop). He settled on the Jazz and is happy with sales now.