Occasionally I've received free gifts when buying Tupperware - the little gadgets that you usually only see given away at Tupperware parties.  Some of them have been really handy so I love getting those, especially as I am not keen on holding or attending any Tupperware parties myself.

A Chinese seller I've bought a few things from also included little packets of craft stickers, and I once received a little packet from a Japanese seller which I think contained tea.  (I don't drink tea).