In the comments, Martin suggested using Schottky Diodes vs Germanium.  They both have a low forward bias, and both would work.  After searching for both types of diodes, the Schottky Diodes are much more widely available and at a lower price.  The main goals of the project is to keep it as low priced as possible and make it as easy as possible for anyone to build and use in their own project, so I think it is a great idea to switch the design to use Schottky Diodes.  The details and diagram have both been updated to use Schottky Diodes.