I'd definitely ask your friend to help, offer her money if you feel more comfortable with that and you can always return the favour when she may want your help in the future. as she knows your circumstances I'm sure that she will be happy to help. I hope that the speech therapy helps your son, my friend's son went to speech and language from an early age, and he's so much better and more outgoing now he can be understood by people outside him family circle. Good luck.