I got the starter kit from v2cigs, switched to SB and am now refilling the carts with ejuice
There are lots of vendors out there that sells empty and/or prefilled kr808d-1 cartomizers.
Almost all the prefilled ones are filled with chinese liquid.
Except one, primevapor. (Unfortunately, they don't ship overseas, so I haven't tried them.)
If you're looking for batteries, then it's what dormouse said, (though I prefer auto ones)
and then there are bigger batteries that could use kr808d-1 cartos,
like vgo, elegant easy, echo, pigcig...
If you're looking for liquid to fill your used v2cigs cartos,
lots of forum suppliers here you can choose.