Fortunately V2 is a KR808D-1 so you are not locked into them for supplies. You can get plenty of prefilled cartos (soft-caps - easy to add juice to) at Vapor4Life.com as well as blank standard resistance cartos there and at many multi-brand vendors.
Buy some e-liquid - cartos do not last as long as some "name" brands claim. But if you keep one damp, you can get 4-7 days use out of one.
One caution - you probably have automatic batteries and autos are dependent on a drag sensor in the middle of the theaded end. That is right where a carto would drip. So always remove the cart from the battery before adding juice and be extra careful to make sure it is not going to drip on the end of your battery. Hold a tissue on the threaded end hole when adding juice, clean/dry that end and puff into the threaded end with the carto tipped open-end down into a tissue to clear the center air channel (if it has a distinct center channel), sop up any juice that is pooled above the stuffing. I do that anyway with my manual batteries because nobody wants juice on the battery connections but for auto batteries, drips could actually kill the battery.
So grats - KR808D-1 is actually the most popular 2-piece threading. And now you know you don't have to pay V2's prices for parts nor be without cartos when they are having stock problems.