Here's a list of what's in the basic kits, and my thoughts (and questions) on their necessity:
Nic base, PG and/or VG: Required, obviously. I'll need to get these whether in a kit or individually.
Flavorings: Required (unless I want to make unflavored juice, which I don't).
Sweeteners: No idea. Do most people add sweetener to their juice, or is the sweetness from the VG enough? Do the flavorings themselves have any sweetness to them, or is it akin to buying unsweetened baker's chocolate?
Mixing Vials: I suppose I can just mix directly in the bottles?
Dropper Bottles: Like you, I've got a few of those leftover from pre-made juice, and will have plenty more become available as I use up my current supply.
Syringes: The kits all come with multiples of each size. Do I really need more than one of each?
Needles: Again, the kits come with multiples. Do you switch out needle tips between ingredients, or is a quick wipe with a paper towel enough to keep cross-contamination to an acceptable minimum?
Transfer Pipettes: Some of the kits have these, but the cheapest one does not so I presume they're not an absolute necessity. Why are they even there, when the kits that have them already have more syringes and needle tips than the one that doesn't? Do they do something a syringe doesn't, or make something easier to do than with a syringe?
Vial Rack: Well if I don't use the vials, then I won't need a rack to hold them in either, now will I.
Nicotine Test Kit: I know how to math, so presuming I measure carefully I shouldn't need such a thing?
Gloves and Glasses: Natch.
Thoughts?