Supporting the developer and getting into the smart, welcoming community are well worth the trivial amount being asked for. There is something to be said about a project that is driven by a uniform philosophy to deliver a unique and singular product. I think a lot of projects suffer from a "too many cooks" problem, and lose sight of their guiding philosophy in an attempt to compromise with naysayers. Zep doesn't do that at all... almost to a fault... but I respect his vision and adherance to keeping PICO-8 a pure representation of his vision.
If price is a problem for anyone, you may already own a copy. PICO-8 was (quietly?) included as part of the legendary itch.io mega "Bundle for Racial Justice."