I like places that find a couple good lines, stock 'em and stand behind 'em, rather than trying to chase everything. Especially since vape shops are generally small endeavors - I got my start in business running a bike shop out of the back of my pickup when I was 16, traveling to local racetracks 6-7 days a week. My inventory was obviously limited (how much can I fit in a Ranger with a hi-top shell?), so I stuck to products I could a) stand behind and vouch for as a user myself; and b) sell at a price that undercut my competitors.
The competition hated me, my customers loved me. The first I ignored, the second was a badge of honor.
That said, if you're having success with Sigelei (I'm a big Sig fanboy myself), keep it going - bring in the 30-watt mini and the temp-controlled 150 when it comes around. If not one of those, the IPV4 seems to be popular these days, and has good reviews - I'd be banking on those, rather than testing the waters with unknown product whose potentially-shoddy performance could end up reflecting poorly on you as the guy who sold the device.
