I think it's a safe bet to say they are using the vanilla absolute... There's really nothing else left. Hope someone tries it and lets us know. I might buy some later, like in a few weeks.
BUT PLEASE PLEASE READ THE FOLLOWING PRECAUTIONS:
The first link I posted above is (apparently) not a product safe for internal use.
I'm seeing some confusion concerning products labeled as Vanilla Absolute as to whether they are solvent extracted or CO2 extracted and it appears there are different forms without explanation for why they may or may not be useful for intended purposes.
The vanilla absolute I linked to before (I cannot edit that post) but it is referred to as a 20x extract... unclear on any differences here, but on their site it specifically states: reserved exclusively for perfume not for internal use.
HERE IS THE ACTUAL LINK FOR THE ONE DESCRIBED THAT INCLUDES FOOD FLAVORING AS A PUBLISHED PURPOSE FOR THAT PRODUCT:
Vanilla absolute soluble 1/2 oz (Vanilla Plantifolia Andrews)
Amber to dark brown liquid
Odor: Vanilla powerful
USE: Perfume, cosmetic, food flavors
Price: 77.80 US $
http://www.essential-oil.org/proddetail.asp?prod=1VanAbs15
HERE IS ANOTHER SOURCE THAT WE CAN ASSUME IS SAFE:
http://www.neroliane.eu/product_info.php?products_id=854
It appears non-toxic but there have been no formal studies according to one source.
ONE WOULD USE A VERY TINY AMOUNT AND I DO NOT KNOW HOW MUCH THAT WOULD BE.
I AM SURE THERE MUST BE OTHER SOURCES OUT THERE THAT MAY EVEN BE MORE AFFORDABLE THAN THIS BUT ADVISE TO MAKE SURE IF NO OTHER INFORMATION IS AVAILABLE THAT THERE IS SOMEWHERE A STATEMENT OF INTENDED USE THAT INDICATES FOOD FLAVORING AS IN THESE EXAMPLES.
I THINK IT'S DEFINITELY WORTH TRYING.
EDIT:
OOPS... THEN I READ IN AN INGREDIENT LIST POSTED ON HERE SOMEWHERE THAT THE E-LIQUID MANUFACTURERS MAY BE USING : Ethyl vanillin
ETHYL VANILLIN is a synthetic compound that is 3½ times stronger in flavor than real vanilla, although the flavor is not quite the same. It is used in the creation and/or manufacturing of fragrance and flavor concentrates of all types.