So, figured out my costs... thank you bulk (on sale) NIC purchases
unflavored DIY 2.4% NIC --> $ 0.0236 / mL
flavored DIY 2.4% NIC --> $ 0.0276 / mL to $ 0.0316 / mL
I budget myself 4mL of liquid per day, but I'm not strict about it... 4mL * $ 0.0316 = $ 0.1264 / day ~ $ 0.13 / day
I have been replacing the coil head in my tank about once every 2 weeks,... $5 / 14 days --> $ 0.357 / day
I don't run a special fridge or freezer.
I don't have any numbers for what it costs to charge my batteries, but I know it would be low... for the sake of argument let's pretend I only charge my vape batteries off of a 4Ah battery pack (supplied by someone else) that I charge elsewhere (for free). Either way, I paid 8 dollars for each battery (which came with a tank+charger). I subtract the $5 for the coil head I took from the tank -> $3 and I will have to replace them once a year ( $3/365.25) --> $ 0.008/day * 2 --> $ 0.016 ~~> $0.02/day
Juice: $ 0.13 / day
Head: $ 0.36 / day
Batts: $ 0.02 / day
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Total: $ 0.51 / day for the normal stuff
I'm still messing around with other stuff... I do have mods, drippers etc,. and a bunch of cylindrical batteries in various sizes, oddly, that's not my go-to equipment. Either way, I'm a low-wattage vaper... so I don't need hi-drain expensive batteries. Most of mine are reclaimed from battery packs.
I guess the last thing I really need to do is figure out the right tank so I can just rebuild/rewick my coils and be happy with the results. I'm guessing when I read this thread from the start, I'll find suggestions for tanks/heads that are good for rebuilding.
It wasn't my goal to do this as cheaply as possible... but when I sit back and look at the numbers, it can be very very cheap. I have also rebuilt a number of ecigs that someone was throwing away... they worked fine after a new coil, battery charge, cotton and juice. I have even retro-fitted a BLU so that magnet wires come out near the light-up tip for simple recharging via a standard Li+ charger yanked from one of those battery packs I mentioned... swapped the hard tip for a soft tip from a different eCig and whamo... re-useable ecig on the super cheap. My "Zef Cig".
I'm starting to wonder though... do I really need to replace the coil at all, well, the Kanthal? I took a cruddy head apart, unwound the coil... cleaned it, torched it, re-coiled it and used it in my dripper. Tastes fine, vapes fine. That would just leave the wicking material... I have some wire mesh, but I have not done anything with it yet. I have also seen a few coils that are supposed to wick on their own mostly.