e-cig kits have dropped to $10 or less from China, and I bought one for someone I know who smokes. I want to buy her a variety of cartridge refills of varying flavors, but do not know if they are interchangeable.
Is there any kind of universal standard where ‘any’ refill works with ‘any’ e-cigarette, or is it brand and manufacturer specific?
There is a lot of interchangeability; like many things, there are really only a few actual manufacturers who make the things for many different brand names. You are going to have to do some research to find the generic model number of the unit you have.
One hint I can give you is that “KR 808” is the most commonly found generic model marketed to new esmokers. It is one that looks a lot like an actual cigarette. Another popular one that looks more like a pen is the “DSE 601”.
A couple links to help you get started:
http://www.vaportalk.com/forum/topic/7581-names-numbers-and-prefixes/
http://www.e-cigarette-wiki.com/index.php?title=Brand_and_Model_Compatibility_Chart