Are you using pre-filled cartomizers or are you filling blanks cartomizers from NextCigs?
The vendor does sell blank carto's on the site. You can easily get new flavors from other places.
I'd recommend ordering sampler packs from other vendors befoe spending a lot of money on larger bottle sized for a juice you might not care at all for once you try it. Once you find some winners from the sampler, you can order more in a larger size.
A couple of vendors that I use frequently that offer sampler packs are below.
Organically Flavored E-liquid | Virgin Vapor | Electronic Cigarette Organic e-Liquid | Electronic Cigarettes
Vaperite | Organic and Natural Flavored Electronic Cigarette E Juice
I agree with DietSalems comments about upgrading. I know that new vapors want a cigarette looking battery, but they are really too inefficient with weak power and short battery life. Once you try something bigger like an eGo battery, you'll find out what you are now missing and wonder why you didn't start out with that.
Start investigating an eGo Twist or eGo Spinner battery. Before purchasing a kit, inquire here to see if members here with experience can confirm if it is a good kit.