Suppose that Billie obtained a hi-fi system and turntable during the pandemic. Furthermore, suppose that, each month, Billie's demand for vinyl records is described by Q = 40 - 4P (and their inverse demand curve is described by P = 10 - 0.25Q), where Q is quantity of new vinyl records per month and P is price per record. Given this demand curve, what is the most that Billie would be willing to pay for a subscription service where they must pay a fixed fee and can then obtain as many vinyl records as desired each month?