Congrats on making the switch!
One thing to remember about the pre-filled cartos is that your usage depends on several factors including the nicotine content, the size of your puffs, the type of e-liquid (pg vs vg ratio) used, and the frequency of vaping (ie do you vape only when you feel an urge for nicotine, or do you vape for taste/enjoyment?) I've heard of people using anywhere from 1/2 to 3 cartomizers a day so I really think it depends on the person. Once you start filling your own you probably won't care how much you are using since e-liquid is pretty cheap in big bottles and you can fill a large tank and be good to go for at least a couple days.
I do think that it was easier for me personally to make the transition using a basic e-cigarette and pre-filled cartos while I researched the many vaping methods and products, and learned how to fill my own cartos and tanks without making a mess. If you're going to go that route and are concerned about price, I'd recommend starting on the 24mg nicotine cartos. Some sites say that these are equivalent to one pack of regular strength cigs but I've also heard that vaping delivers slightly less nicotine than smoking so its advised to start out at one level higher than your current nicotine level. Also, its up to you how much you decide to vape so I'd think its better to have something strong that you don't need to vape as much of as compared to having to vape nonstop just to satisfy your nicotine craving.
All of the kits listed here look pretty good, I'd also recommend checking out the
Volt standard starter kit from Smokeless Image. The kit is the same price as the G6 and also includes 2 e-cigs and the same items (minus the carrying case) but the upside is that the mah is higher, meaning higher battery life (they will last longer before needing a charge.) The "180" you are using now refers to the mah of your battery; the G6 automatic is also 180mah, while their manual is 280. Volt is 220 for the automatic and 320mah for the manual. Automatic= the shorter e-cigs that activate from you inhaling Manual= There is a button that you push when you want to take a hit.
As mentioned already, you should start off with 2 e-cigs so you have something to vape while the other is charging. You may want to get 1 automatic and 1 manual to see what you prefer.
One other good thing about the Volt is that you can select a flavor sampler pack w/ 5 different flavors for your pre-filled cartos.
Good luck!