Aloha From Hawaii!
Okay, not sure if the prices are in line with what's being charged in your neighborhood, but for a heavy smoker, the cartidges will be cost prohibitive. I know you wanna slow down and hopefully quit, but I think that the cold turkey when you're ready method will be the best solution for you.
I quit smoking and drinking once for three years, but once I grabbed a puff (wasn't thinking and someone offered me a smoke), I knew that was it. Although I had stopped smoking for three years, I still craved it...A LOT! I knew I wasn't ready, but decided to try anyways.
Best of luck with your endeavor!
Mele Kalikimaka (Merry Christmas in Hawaiian)!