Identification of shelf brackets
Using the term "shelf clips" I was able to locate only one resource, a company called Locksco which has a clip that appears to be similar to yours.



During the search, I saw also the term "metal cabinet shelf clips" but using that search term did not present the previous location/link. At US$20 for quantity four, they certainly are expensive.

Note also that no references of scale are apparent. They could be too small or too large for your purpose.

Additional searches proved fruitless.