One of my uncles is a retired clocksmith and he give me few years ago a cardboard box full of broken alarm clocks. [link]
(Maybe about 25-30 clocks total and one smaller container of broken wrist watches etc.
Now i have dismantled most of the alarm clocks and left only four best looking mechanism intact, if i need whole mechanisms for some future projects. So all the gears from those other clocks are in that black bowl. I have already used about 50-100 brass gears for my previous projects, but there is still great materials for maybe about next 5-8 years, if i don't find more old clocks anywhere.