Go right out to the garden store and buy some small plastic pots for you starter containers. Or: you may consider green alternatives. You might want to think green for the environment and green in your wallet.
The above photo is of fall vegetables that are about ready to be transplanted. One tray is made up of used milk cartons from Randolph Community Middle School. The other tray has reusable plastic yogurt containers. The containers have one or two small holes drilled into the bottoms for drainage.
Which one seems more efficient in regards to spacing and the number that fit into the tray? The ratio is 32 milk cartons to 15 plastic cups.
Ask a school age neighbor if they would like to earn some money. Have them collect the milk cartons at school so that they can be reused. I pay ten cents a container. This teaches reuse, grow local and ways to generate income. If they get permission to wash the milk cartons at school it may stimulate conversation about green living in the class and among other students.