You can find these trays at Walmart in the kitchen area. They run for $1 for a pack of 2 or 3, depending which one you get. A couple of years ago I purchased a set of black trays that were for the same price at CVS. Unfortunately, I haven't seen them there in a while but if you're lucky, they might still be available.
I took pictures of different ways you can store these trays in your drawers just so you guys can get an idea of what I mean by the different variations for storing them.
An example of how I would organize my lippies from lipglosses to lipsticks.
This particular drawer is by Sterilite.
Disclosure: This product was purchased by the author of this blog.