Green Smoke is way over priced, and the 1 cartridge is not equal to one pack. Check out this forum if your considering e-cigs loads of great info for the newbie.http://www.e-cigarette-forum.com/forum/
It is equal to a pack as long as you only take as many puffs from the green smoke that is equal to one cigarette. This confuses many people since they sit there and smoke it tell the cartridge over heats and the substance inside becomes burn't and all the nicotine is expelled and a very burn't taste becomes present. It's the rule of life, you get what you pay for, as long as your not a dumb ass, you got to do your research before investing in a product. Green Smoke is one of the best, if not the best e-cig out there. The units are comprised of quality pieces in fact I've had the same battery for a little over two years and I haven't had one single problem. The cartridges are satisfying nicotine and taste wise. If you buy a $40 e-cig, you won't be happy, I guarantee that. It's a little expensive first off, but after two months you'll be saving money. Equivalent of five packs for $13 dollars, good deal in my books, in my Canadian books anyways. I have no idea what cigarettes go for in the States.
That's my two cents!