Hi,
my experience is very limited as well. However I'd like to add that there certainly is a demand in Munich. Surprisingly there aren't many private kindergardens even though the demand is higher than the supply.
Somehow I suspect that this is due to the fact that the public and non-commercial Elterninitiativen get sponsored by the council. I don't know whether you would get sponsered if you were profit-oriented?
If you don't get any subsidies it will be very hard to compete with the public ones, even if you offer a bilingual education.
The hardest part however will probably be to find a good location. To be able to open a koindergarten in an apartment/house previously used as a flat, you would have to apply for a "Raumnutzungsgsänderung" (change of use) and all neighbours would have to sign they don't mind living next to a kindergarten. This is tough.
Also you'd maybe need a garden, etc...
If your german is good enough you could try
http://www.elterninitiativen-muenchen.de, this is a page dedicated to helping new Elterninitiativen.
hope this helps,
love,
kati
ps: I'd take a place (fulltime) if you manage to make it work (and if the location isn't too far off).