Started working when I was about 10. And you often pick things up for a specific project, or in some cases as a tax offset. Last piece of kit I bought was about $200 in light-bulbs because that's the style I'm working in now-- reglobing -v- dimming.
Most of the camera stuff I picked up over the years. One whole package was payment for a docu as opposed to an actual check they didn't have.
SR3 was the main purchase, with lenses, when my dad died (2007) with a good bit of that kit like many of the lenses and the mattebox and follow focus etc, and I had far more money in my pocket than brains in my head. Though granted, in that case, it made me a better DoP, though never made me money (and probably never will).
Bought my first Nikon, god, I don't even remember when, and pick up lenses over the years-- flea markets etc.
Rokinons rent in LA pretty well-- so investment with the proliferation of EOS mount cameras.
etc etc etc.
Also that's all camera stuff listed there. I have lights as well--mostly PARs, 1 small Arri Kit, though that was purchased long long ago for a documentary shoot of interviews--- the PARs i picked up for a film shoot where we had to do some high-speed without time to really re-light, so we used series of pars through some diffusion frames and the like to make up the stop loss going to 150fps. I got them because they were cheap and keep them with me because, I'll use at least 1 on every shoot-- but that's roughly a $100 light, give or take, -v- a 3000 kit.
Picked up 3 red-heads for $25 a piece when a shop was closing down. 2 still work, one is for parts etc etc.
If i did go buy an Kino Kit, i probably wouldn't get much cash for it, in truth; as generally speaking, it's much more cost effective, looking for results and not impressing a client with my name branded on something, to get a 3 ton lighting truck with grip for $500/day list (not counting discounts you get when you start working with a rental house). I mean I could in theory rent it for less than a rental house ($15/day maybe $20) but then I'm also on the hook for it getting beat to hell if i want to continue renting it out. And buying all the crap for it, and the bulbs. Why do that when I can rent one, and let someone else deal with that stuff?
Same can be said for cameras for the most part, though there is a great prevalence in the world in which I work, of the expectation for a camera for a few dollars with a DoP along for the ride. I do not like this situation, but it seems to be a growing trend.