Unless you choose to keep buying things purely from a hobby aspect, after a while things can level out nicely.
Where I am cigarettes run $9/pack. My first 6 - 8 months vaping, even with buying things fairly often I was still only running about half the cost, $4.50/day. After about 8 months I got into using good VV devices, and had several DIY eliquids that I really like (been vaping the same mix for two years now); my running cost nowadays is about $2.25, which includes $1/day towards my next nice PV, the other $1.25 being towards consumables (atty/carto, DIY supplies, batteries). Right now I'm on a bit of a spending surge, running into some atomizer early failures, but the $2.25 is still about right over a wide time window.
My gear and eliquids work really well for me. Honestly, I have no idea when I'll buy my next PV -- I have a high performance, rugged, VV tube, for cruddy environmental conditions, a spare for that tube PV that hasn't been used, a good VV bottom feeder for general all-day use, an ego twist in the car for backup (if I forget spare batteries, or want a "disposable" for use on a boat), and a tiny SD keyring (it hasn't seen much use, but nice for real stealth).