I think that the basis and foundation of biodynamics is incredibly interesting and holds great value in modern times. Most people get so hung up on very minor aspects of biodynamics like the buried cow horn, and stiring 500 times in one direction, then 500 in the other etc. Too many people get hung up with the symantics.
If you look at the practices, many of them have sound logic behind them. Bury the dung in a cow horn? Some websites and books may tell you that the horn acts as an antennae capturing cosmic forces. Reality? Who knows there's probably microbes within the horn that aid in the break down of the manure stuffed into it, or perhaps a reaction between the manure and the horn material that aids the bacteria.
In making the BD 500 spray you must mix it in a particular vessel, and it should be done at a particular time of year. Yep, mixing in a vessel made from the wrong material (perhaps aluminum) may kill off the good microbes, doing it at a particular time of year probably relates to the temperature of liquid for maximum microbe grown and reproduction.
Stiring it 500 times one way then the reverse. Once again, some literature tells you it's creating a deep vortex to attract energies, then changing direction creates chaos within the mix. Another way of looking at it is that you mix it really well and it aerates the mixture as well.
There's quite a bit of mystery surrounding Biodynamics but in recent years, modern methods have started to dispel much of the mysticism and replace it with simple reasoning and modern scientific methods.
I saw a biodynamic farm on tv where they were mixing up bd 500 in huge tanks (looked just like fish tanks
), pumping and aerating the mix, watching the temperature keeping it at the ideal temperature for the microbes.
Whether it's suitable or achievable at a backyard level I don't know..
If you play around enough with manure tea and liquid fertilizers, and practice organic techniques, your probably on a fairly similar path.
Backyard Farming Forum
Plenty of stories about biodynamics in farming. Does it involve the buried cowhorn like for paddocks? Or just spreading their special microbes, etc (something 500?) on the soil? 
