Stay with it, Phil. I've never used a cartomiser, so I don't know how to fix your issue, but when I talk to people who are wanting to get into it, I recommend a Kanger T3 clearo on any eGo-style battery. An eGo Twist or a Spinner is never a bad bet, and there are tons of places to get off-brands of them. There are literally hundreds of different places to get juice, just google 'ecig juice' and start clickin. I like The Vapor Room's juice, as well as ECBlends (REALLY cheap), and there are a couple local stores I've bought from. I also recently ordered from eHope too, but I'm still waiting for that to arrive.
My advice; stay with it and don't be afraid to spend a couple bucks to find what works for you. Just remember how much you used to spend on smokes and it's much easier to spend on vaping gear, even if you get stuff that sucks a few times.