Here is a cool find on Ebay. 50 plastic gears of different styles for 3.99 plus 1.98 shipping. Looks like they sold many already. Look down on the page, they even have other gears for sale. John
I got two bags of the gears quite a mixture of gears all hard plastic but nice for building things but not small enough for motor in Z scale engines large and small worm gears flat ones and double with small gear in middle. nice price for the number of gears you get!