Where to buy sourdough culture?
yesterday I've seen a great danish film about a baker who had 18 types of cultures and the light bulb has been switched on in my head. I've a working culture from Reinhart's book and using it with great success, but would like to experiment with new ones.
Do you have any idea where can i buy sourdough cultures? I've googled and found this: http://www.sourdo.com/ 
Is there any other source to get sourdough culture? And let me forgive my newbie question. Generally, sourdough starters are made from whole wheat exlusively or it can be made from white flour? As I'm prefering the ww ones.
Thanks for your time.