Look for labels in plastics or 'blank credit cards', google (include your areas/country if you get too many results) and you should get results.
Maybe too many results.
When you get a company that sells in your area/country you may want to call them and see if they sell in small amounts. (If it is really small amounts you are after, they might send a few samples for token money.)
There are very many options in plastics, chemical make-up, hardness, length of time it will stay stable, colour and colour fastness, and a lot more.
Depending on what you want to do with it you might be able to find what you need or not, even for someone working with plastics it is hard to predict.