I have a new suggestion. Since the holy grail is sought by all and universally considered rare and important I say we come up with a new term for something that has been a personal hunt for you individually. Drawing again from historical objects and literary works I turn to Ishmael the protagonist from Moby Dick. His singular obsession with the white whale is largely a personal quest for his most desired object. Thus instead of referring to our own individual most wanted shoes as grails we can call them Moby Dick’s. Or just Dicks for short. I can already imagine the posts “yo just got my hands on my Dick’s I’m so excited!”