I'm not really a picky flavor vapor but some of the stuff I've made just terrible. Really only thing I've liked diy so far is simple capella vanilla custard at about 15% with a little sweetener. I'm kinda frugal, cheap, tight etc.. etc.. so pretty much anything I can do to save I'm all over it including the cheap store bought but that seems hit or miss as well which is why I want some good diy that I can control the consistency / quality of.
I should be frugal but I have a tough time with that. Anyway I agree with you about store bought "repeatability". Even the relatively expensive brands while still good (usually) vary from order to order and sometimes by quite a bit.