I use the cheap, single sized yogurt containers from Krogers (not the Yoplait which are angled wrong). Then poke a few holes in the bottom, the sides are slick, you can write on them and re-use for a long time. I also use cottage cheese containers as plant starters. All are durable, light weight, easy to store when you aren't using them and "squeezable" to assist in removing the new plants.
