New Yorkers with lighter wallets need not despair. There are a number of troves for the treasure seeker, none more enticing than Posteritati, a store on Centre Street, which has been in operation as a business since 1995. A browse through its recent acquisitions, online, led me swiftly to a bunch of Antonionis from the early nineteen-sixties—“L’Avventura,” “L’Eclisse,” and a sumptuous “La Notte,” with the face of Monica Vitti drawn in black-and-white save for her candy-pink kisser. Or how about a 1973 Japanese poster of “Charade,” featuring a head-scarfed Audrey Hepburn against a backdrop of blazing blue, for four hundred and fifty bucks? A steal. It would be like having a patch of sky on your bedroom wall.