Good morning. Welcome to the forum.
There are already a few parent-child groups around, and many of course change with the seasons. As the child of the instigator grows, so the pairs needs change.
And many of the non-specific groups are free, or ask for a token contribution towards the cost of room-hire. (2-5chf)
There are enough "Spielgruppe" around (google it), where you might be able to ask to use the room for an hour or 2 a week, working around their timetable.
There are "singing groups" in the local language which ask between 10chf and 20chf a "lesson", and parent-child gym "classes", asking 70chf for the season (October to Easter).
Otherwise, Gymboree has made it to Switzerland, though as an attendee, this is a little expensive as there are also the indoor playgrounds offering unlimited time on similar equipment. You could buy a franchise? Though personally I didnt find this financially viable. Maybe I'm too greedy or lazy?
For room rental, you can check out www.comparis.ch .
Hiring people may cost you between 20-40chf an instructor, based on skill level, and what you expect of them.
Make yourself an initial financial plan based on these ideas, and then see how you feel.
And check out this website, to see what other sort of businesses Expats have set up here:
http://www.xpatxchange.ch/