smart pots are great, but once i found these i was sold.
much thicker, square base, cheaper, handcrafted in Norcal.
http://www.leevalley.com/en/garden/page.aspx?cat=2,51603&p=69037
one of the big advantages of fabric pots is that they dont heat up in the sun like plastic ones, on a hot summers day you can feel the side of a fabric pot and it will be cool/warm, when a regular container ir friggin HOT.
i am a firm beleiver in fabric pots.