Im in Wales, UKHi,
Search on "IR reflective sensor" with your favorite distributor. RadioShack used to sell an ancient one. Here is a Digikey search: https://www.digikey.com/products/en/sensors-transducers/optical-sensors-reflective-logic-output/556?utm_adgroup=Sensors & Transducers&utm_source=google&utm_medium=cpc&utm_campaign=Dynamic Search&utm_term=&utm_content=Sensors & Transducers&gclid=EAIaIQobChMI6szQj9_A6QIVUr7ACh0wVgUaEAAYASAAEgJN6PD_BwE.
I show the whole one. Click on Sharp to get a more limited set. Sharp, Sony, Vishay are big names in the field.
I am reluctant to ask where you are, as it doesn't matter to me, but it might make a difference for recommending sources. Are you in the North America or Europe?