After a lot of research I have found a lot of things and some very good information resources that I would like to share.

Basically, there are loads of free or cheap alternatives to the expensive microbial products on the market. In fact, I found so many that I am still catching up with all the info and it would be impossible to mention everything here, so I'm gonna mention some stuff and share the resources so that people can do your their own research.

Note that many of these cultures have a LOT of different names since they are not owned by companies and trademarked. You can get these cultures from people who share them for free, buy them from the web, or sometimes grow your own from scratch. You keep these cultures like pets and eat their waste as a healthy drink or sometimes eat the cultures themselves.

~ kefir - microbial culture that grows on milk (seems to be the most popular culture)
~ water kefir - kefir variant that grows on Sugar water (not exactly the same as kefir)
~ kombucha - fungus culture that grows on tea (apparently popular at Google cafeterias)
~ ginger beer plant - culture that makes real ginger beer (not necessarily alcoholic)
~ rejuvelac - grains are left to ferment (sprout) for a few days in water to make a fizzy drink
~ raw vinegar - unpasteurized, contains the living "mother" (apple cider is most popular)
~ wine - not sure it has living cultures but it seems to improve health for some people
~ real ale - unpasteurized beer (this really changed my idea of what beer actually is or was)

Microbial Nutrition is a Yahoo group that I strongly recommend:
http://groups.yahoo.com/group/Microbial_Nutrition/

It has the most variety of information about microbial cultures (including Effective Microorganisms) and fermented foods in only one place that I have been able to find so far. It has lots of useful links and many recipes in the files section.

For example, one recipe from the files section is a homemade EM recipe given by a Japanese guy. It basically is: 1 part molasses, 3 parts herbs, add water, let it ferment in a sealed container. But just saying this does no justice to the information, so I recommend everyone to have a look.

Fermented foods UK is a group for people to share cultures and info in the UK:
http://groups.yahoo.com/group/Fermented-foods-UK/

These other three groups are more specific:
http://groups.yahoo.com/group/Kefir_making/
http://groups.yahoo.com/group/original_kombucha/
http://groups.yahoo.com/group/GingerBeerPlant/

These are only a few of the drink cultures, and there are many dairy cultures like the buttermilk plant, viili, fil mjölk, piima. And there are also lots of fermented foods like sauerkraut, kimchi, tempeh, nattou, miso, idli, dosa, sourdough bread, yogurt, aged cheese, ham, chorizo, etc.

Many of these microbial cultures, foods and drinks are mentioned in detail on the lists. Some of these are also discussed here at CureZone and I know there is the Kefir forum and the Apple Cider Vinegar forum.

Kefir Grain Support Forum
//www.curezone.org/forums/f.asp?f=295

Apple Cider & Fruit Cider Vinegar Forum
//www.curezone.org/forums/f.asp?f=483