Commericial Invoice
You never need a Pro-Forma invice for anything, never.
You do always* need, always* need the commericial invoice.
*Always does not count for stupily obviously inexpensive items or some personal items BUT if there is any doubt what so ever that the value is not stupidly obviously inexpensive the items will be held for the Commercial Invoice.
As seen all over this board, Items with a value of less than US$200.00 are exempt from taxes, import or sales.
g'luck