Apple is apparently refusing to accept cash for iPhones. I have a feeling this policy will last less than 24 hours, as there's significant intersection among the set of people who would purchase iPhones and the set of people who will get into quite a snit about "This note is legal tender for all debts, public and private."
Update: Neil Bartlett points to \<a href="http://en.wikipedia.org/wiki/Legal_tender%23In_the_United_States"" target="_blank" rel="noopener noreferrer">this Wikipedia article that says companies can refuse cash if the debt doesn't already exist at the time of payment (as would be the case when purchasing an iPhone). That's what I get for getting my legal advice from 30 Rock.