Just when I was starting to despair about buying pots--free and environmentally friendly all at once ....
Tear a newspaper into 4" strips. No need to be fussy about 4", a little more or less is fine. You'll need one strip per pot. Using a glass the size you want for a pot (I use 3" usually), wrap the top 2" of the newspaper around the glass, leave the bottom 2" to fold over the bottom of the glass. Fold the paper at the bottom of the glass over and hold with a small piece of tape if necessary. Remove from glass and Viola! A biodegradable pot.
When you put your plants into the garden you should remove the piece of tape, open the newspaper at the bottom and allow the roots contact with the soil.