DIY is where most eliquid will happen regardless of government. The driver is cost. A $50 (US) bottle of 100 mg has 100,000 mg of nic, the same as the smoke from 5,000 packs of cigarettes. PG and VG are dirt cheap commodities. Flavoring doesn't have to be expensive. My DIY cost of materials is 1.2 cents per ml, about 8 cents a day, about $30 a year. May be plenty of people are willing to pay 50 cents per ml for premix today but that's going to get old eventually. A lot of kids, who smoked little or none don't care about nic, don't need it in their vape. There's no stopping them from buying the other three ingredients and why should we? I've said many times I wish ecigs had been around when I was a kid. Regardless, don't sell anything to kids if their parents might not approve but let parents decide if their kids can vape--off school property of course.
BTW I bought a 120 ml bottle of all in one flavoring for about $14. I use it at 1% so one ml flavoring per 100 ml of e liquid. It tastes fine. I vape something less than 200 ml per month so that bottle of flavoring could last me 60 months, 5 years if it doesn't spoil. Basically vaping is free. It's hard to tax free.