Do you get two for the 75 or 100 dollars? I'm not sure I'd want to wear an insole in just one shoe. EDIT - this is covered in your FAQ, sorry.
"Yes, we will provide a matching insole with the same feel/weight/size as the power-producing insole so the user doesn't walk with uneven steps."
Secondly, why would you advise this over a wind up charger?