Dr. Earth POTting soil is good (but pricy) stuff. It is fully amended and ready to go to feed the kiddies for about 3-4 weeks.
Look into POTTERS GOLD and see if it's available in your area yet. I use this and I LOVE it. This soil is prepared from scratch like "SUBS SUPERSOIL" and feeds completely for 4 3-4weeks.
If you feel like preparing your own just search Subs Supersoil here.