why not just take the pedals off a pedal bike whilst they learn to balance and save that 100 quid spent on a posh bit of park-parent jewellery?
next put the pedals on and the stabilisers, let them learn to pedal followed closely by taking the stabilisers off and hey blummin presto
even suggested it to my LBS (who stock every kind of wooden/Al/Ti balance bike in the country) and they said - 'yeah, that is quite a good idea'
maybe its the fear of a 15mm spanner?
[rant over; discuss]