They touted it in California as tax free. The price was lower even after shipping. They eventually sent a letter to all of their customers in California that they were being forced by the CA State Franchise Tax Board to report taxable sales and the customers name and address at the end of the year. They will go after the consumer for the tax. Your client must be very careful.
Different states have different laws.
I'm sure its even more of a mess when you start talking international.