Based on the recent post about the disposable Montreal subway tickets with a super cheap nfc chip (and amusingly on a paper ticket with a a printed on fake smart chip connection) it should be super cheap to have an automated kiosk that pairs your drink order to a paper cup that when a barista swipes shows your cup your order shows up or fills it automatically.
Seems like it would be cheaper to have a simple QR code be thermally printed on the cup. A fraction of a penny's worth of chemical spritz on the bottom of the cup would do the trick.