If you mix your own juice you're approaching savings that are better on an order of magnitude.
Three 120ml bottles last me close to an entire month. Local stores around here are also a rip-off (near Austin, Texas).
Vaping is something I do A LOT of while post-processing photos! Do you perhaps have a photographic interest?
That's more than 10ml a day! I know you're going to disagree and try to convince me otherwise, but that is an INSANE amount of liquid.
I should try and cut back some and reduce my nicotine dosage of 1.5mg down to 0mg but I don't mind the nicotine.
I'm also addicted to coffee so about 2-3 full Yeti cups a day. Woe is me!
once i found some diy recipes that i enjoyed, i made a pair of 120ml, and the cost savings from those two bottles alone covered all the ingredients and equipment (beakers, stirring rods, scale, bottles, etc). diy is especially worthwhile if your device guzzles juice like my geekvape griffin tank does.
diy or die on youtube is a great resource, here's one of the recipes i make regularly: https://www.youtube.com/watch?v=QlI8CvT8SCA
If you're buying domestic juice you pay a premium for nothing special, from what I can tell. Also, the chances of it being made in a proper factory are basically nil. It's often someone else's DIY garage juice at a 10000% markup.
I haven't kept up with the new FDA guidelines since starting DIY about a year ago, but from what I remember a lot of the little garage brands are going to be in trouble. My buddy used to work at Apollo out in Concord and I know they take their juice seriously. I think it's shitty, but it's not because the line is dirty haha. Molecule Labs out in Benicia has a pretty cool facility as well.