An interesting complication is if the radio is supported by large private donations. Then a non-wealthy listener might want to donate so that wealthy listeners would donate. Then the question is how much to donate. If wealthy donors behave like you, you could donate a fraction x of your income such that donations of x of wealthy donors' income would suffice to support the radio. If wealthy donors behave like you in deciding whether or not to donate, but behave differently from you when deciding how much to donate, you could adopt the policy of making a minimum donation in the hopes that wealthy donors will similarly make donations, and that enough of them will decide for their own reasons to donate substantially.