In 2008 I mentioned that a one hundred billion dollar banknote was being auctioned on eBay with a high bid of AU$87.
Today, you can buy a one hundred trillion dollar banknote on Amazon for US$0.90 (plus $4.94 shipping).
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