It's an amazing project. The structure of the microscope is made of folded paper, meaning not only is it cheap, but it can be flatpacked and shipped cheaply. The lens is also a cool innovation. They use the glass balls that rattle around inside aerosol cans as a 140x magnification element. The optical quality would normally be horrible, but since such a small image is focused through it, the quality ends up being decent. The balls are mounted in electrical component manufacturing tape, meaning you can just pop the tape in, with no alignment or scratching issues.
Here's a wired article on the project: http://www.wired.com/wiredscience/2014/03/paper-microscope/
Here's an old TED talk:
http://www.ted.com/talks/manu_prakash_a_50_cent_microscope_t...
I've worked with them to pilot the educational use of these microscopes in local schools. Feel free to ask me any questions about the project or the design.