We use the extra money that I have saved to pay down bills and to have actual vacations
According to my spreadsheet, I have saved $5,509 in the 2 1/2 years I have been vaping. But I do have some pretty nice gear. There have been things that I have PIF to others but those still go in the expenditure column. Can't mark it off as a charitable expense. (eliquids that I just didn't want went to good homes

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I gave up the spreadsheet after a couple years, was limiting my vaping expense to 1/2 of what I was spending on smokes. Found I wasn't coming close to spending 1/2, but I'm a frugal vaper.
I DIY my own juice, found I liked my flavors much better than pre-mixed, the cost savings is just a bonus. I like my own home cooking vs. many restaurants also...
Spent a couple of years vaping my own home built mods, stuck with the toppers that were working for me. Passed up on the pro-tank/nautilus craze, never owned one, bought a Kayfun + when the version 4 came out and they were on clearance. The clearance bin and holiday sales have always been my main shopping experience. It's been more useful to figure out how to get whatever I have to work properly, that chace the latest fad.
If I use one of the signature calculators to figure how much I haven't spent on smoking, I'm over $20,000. Not sure how much I've spent on vaping, but it's nowhere close to that, and I have supplies, mods on-hand that will last me for a couple, few years without spending more, except for a bit of PG/VG and flavors.
I pity the new vapers that are being bombarded with each new mod or topper, promising the ultimate vape. So hard to choose what will actually work and keep them from smoking, the main reason we're all here.