There are many bill changes out there.
100 dollar bill change, Hundy 500, Heiny 500, Prophet, Extreme Burn, Slow Burn, Infinity Switch, etc.
All these are so simliar its not even funny. They are basically the same gimmick with a tiny difference. They are usually a bit different in the way they are constructed, but the basic method is the same. If you buy 1, lets say Extreme Burn, you can basically figure out all of them. The Infinity Switch is different to these, but is similiar to Garcia's Greed. I would recommend the cheaper out of Hundy, Heiny, Prophet, Extreme, or Slow. Get one, and get all.