Some of the most expensive ones are here...
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and here
ElectronicStix.Com · The Titanide Themis
And Provari (Only battery unless you purchase the Z-Atty with it) is supposed to be one of the best, but I have never used one,,, I might be getting one soon
There are tanks that can run upwards of $300 by themselves
There is one that I found, but can't find it now that is really pricey, but supposed to be really good.
I would never purchase it.
Most Popular is probably Ego Twist and Spinner and then the Vamo (which is not bad for the price)
Best can be slightly subjective. However, consensus shows that Provari is one of the best VV batteries out there.
I wish they would change their design a bit and make it closer to the Vamo, but with the quality of the Provari.
Doesn't even have to be VW, just make it a bit easier to use and navigate.
Vamo, is (in my opinion) the best for the price, for just a battery. And I do like the VW better than VV on it, it vapes better
and on NO2 setting.
For Tanks, that is far more subjective, as no one tank will fit everyone. You will have to find what works for you.
I use Vivi Nova Mini's, they are my favorites, I do not like Bottom feeders.
The Nova Pyrex 3.5ml is pretty good also.
I also have a Drunker that is ok, but finicky, as well as an AGA-T2 that is also finicky.
So, for me, the best is the Mini Nova's.