As my little seedlings outgrew their hot box, and started moving to bigger and better digs I've been transplanting them and setting them in a sheltered space outside. I've been using homemade paper pots that are free and biodegradable.
And all it takes, is a phone book, tape and a straight sided glass the size you want your pots!
Rip out the pages of an old phone book, fold in half (the hot dog way) and roll them around your glass. I'm using a water bottle since that's all I could find with straight sides. Put a small piece of tape to hold it in place, be sure there's enough overhand to fold over the bottom. (You can use newspaper too, just cut strips the right height)
Fold the sides down to make the bottom of your pot, flatten well and secure with a bit of tape. You can press the cup down on a table to flatten it out nicely. See why the sides have to be straight, otherwise it would be stuck on the bottle!
TaDa! fill with plant and good soil, write the plant's name on the side and fill up a tray with little seedlings! When you go to plant them in the garden you don't have to worry about root bound plants or disturbing them too much. Just cut the sides open and place in the ground paper and all.