According to this 1959 US Embassy document, it costs Rs.500 for a Yeti search expedition permit. You are allowed to photograph or capture a Yeti, but you are not allowed to kill one or shoot it "except in an emergency arising out of self-defense."
Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. His new book is Maker Dad: Lunch Box Guitars, Antigravity Jars, and 22 Other Incredibly Cool Father-Daughter DIY Projects