i use 90ml about 3ml a day but i make my own so its maybe 6 bucks a month , i use a genesis style rba so i havent bought any supplies in 6 months . its the cheapest way to go a sheet of ss mesh / cotton ball and 28ga wire maybe 30 bucks total will last aleast 3yrs maybe more , ive been vaping for 3 yrs and found thru trial and error spend your money on the front end and you will save a whole lot more on the back end (provari +batteries/charger=$250 AC9 rba =$125 +$30 wicking/coil DIY - nic+flavors+bottles+syringes etc $200) you will be around the $600 range and i did not get all this at one time it was over the years ive collected and learned but im at the point now i donot waste or throw money away buying every new carto that comes out only for version #12 to come out a month later, when you get to the point i am at now i can go atleast a year b4 i buy any thing and that would be flavors ( i like to only keep fresh flavor drops they are cheap any way $3 for 15ml which will make atleast 3-5 bottles of juice) if you enjoy vaping over time you will become a smart shopper the hard part is finding out your likes and dislikes ( how do you know if you dont spend the money)