Yes, I have some of those that I brought from Ikea for free.
They have near the Help Desk a place with different hardware parts that you can take as spares.
I actually took some random parts I might need and took some of those
mcmaster carrv has a pretty exhaustive inventory of all things machined. i didn't see those in a cursory look - their catalog system is a labrinth on phone - but their resource desk is helpful and would know right away. www.mcmaster.com