Just starting. I'm shopping around and finding "starter kits." These look a little expensive given they only provide three cartridges or from what I can tell ~30 cigarettes. What additional costs would there be after buying one of these?
One I've looked at is Pure. The prices look great, but haven't found any reviews in this forum. Has anyone here tried these?
How long does the juice typically last?
That's going to vary from person to person. It all depends on how much you vape and how you vape. I use a Mod (Chameleon model) and drip with low resistance atomizers, so I typically go through 3-6ml per day. Some people might go through less.
Roughly, how many cigarettes would that be?
You could jump to an inexpensive mod all you need is an atty which he can provide for a little extra http://www.e-cigarette-forum.com/forum/e-cigarette-suppliers-forum/160858-3-7-volt-510-box-mod-2-14500-trustfire-batteries-charger-30-free-shipping-plus-20-ml-juice.html
There is absolutely no way for anyone to tell. I highly suspect that I vape more than I smoked because I tend to chain vape. The thing you have to remember is that vaping isn't like smoking and we don't absorb as much nicotine vaping as we did when smoking. In fact, we probably only take in 40%-60% of the nicotine in the liquid. The nicotine uptake is also slower and smoother with vaping, plus you aren't inhaling all of the other chemicals associated with cigarettes, so it doesn't feel the same.
There really isn't a way to compare cigarettes to e-cig cartridges or cartomizers, and there isn't a way to determine which nicotine level any one person should start using. There are some people who smoked more than a pack per day, but can't vape nic levels over 18mg. OTOH, there are people who smoked half a pack or less and have to vape 24mg to stay off the cigarettes.
Vaping is a lot of experimentation with both the juice and the hardware to get to that "sweet spot" that satisfies you.