My two cents... I am a potter... OK a potter of limited experience but I do make SOME PRETTY GOOD POTS.
If you are looking for just any old pot to train your tree or to display it at a reasonable inexpensive price go to
http://www.bonsaimonk.com/ The monks have some really good prices on Mica Pots and on mass produced pots from both Japan and China.
If you are looking for something different, something that not everyone else has you should go to a potter. As Carl suggested, Dale does excellent work. Sara is my personal favorite and Kevin has shown us that he is a force to be heard from in the Bonsai Pot Arena. I hope to have some pots available on this site later this week, you will have to decide if they are worthy of your attention..... But I can assure you.... even guarantee that a professional potter is going to give you something different an unique and well worth the extra cost!
I must also agree with David, the best case is to see the pot in person, even have your tree with you, then you can really determine the correct pot. The net (even catelogs) are wonderful, but a 2-D image isn't the same as first hand!
Remember in most cases.... You Get What You Pay For!
Jay