i have a friend who has this, and so did both her children who are now walking - the third child is only 8 months old so not yet walking. Both the "big" ones started walking "later", ie; at ages 19 months and 22 months, because of the tonus. The first child went to a physiotherapist, but i dont think he wore special shoes..
If they are required by the doctor, wouldnt the health insurance pay?