My daughter did something like this as a door to door "bigger or better" scavenger hunt with her youth group a few years ago. They ended up with a giant teddy bear! I read a book written by Canadian man who started out in 2005 with a paperclip, and one year later had traded up to a HOUSE! His name is Kyle MacDonald and the book is called "One Red Paperclip" . It was a fun read. Here is a wikipedia list of his trades:

http://en.wikipedia.org/wiki/One_red_paperclip

That is what JACKS based the first 3 rings on... many years ago. I'm just revisiting the idea of another ; )