Thanks for the question.
Name your own price has been an interesting experiment for me and it's working out better than I had expected.
I didn't want to prevent someone from being able to learn about our Universe just because they can't afford it.
I am very interested in helping people understand how awesome and beautiful our Universe is (and humongous, dangerous, and fantastic). At the same time I've spent almost a year of my life on this and would love to be able to continue to dedicate my full attention to this project.
If you're a school or corporation you need to purchase a license (at a fixed price). Contact me for details. Otherwise the only limit is that $0 isn't really buying anything (and note that both Paypal & Google take around $0.30 + 2.5% of the purchase price for their services).
There's no upper limit.
Print
