I acquired a Smoke 51 Duo from a friend, bought the charger and some cartridges tonight and, of course, paid the same amount that I could have for a starter kit for a better e-cig. Oh well. Anyway, I was just curious if the cartridges for these could be bought cheaper on a different site or if I can get some of the fluid and put it in the cartridges I have. Also, when I screwed the cartridge on somewhat tight, it was harder to inhale, so I loosened it up slightly and it's easier. Is this a normal thing? Thanks!