The closest I could find showed up under Radiography Clip in Google Image Search. I can't be sure, from their images, if the pincer part is exactly the same as yours, however. There are also similar looking items listed under Dental X-Ray Film Clips. As to where either of those items I mentioned can be bought, they're listed on a site called Alibaba.com, of which I know nothing. Both items seem only to be available in Pakistan.

Hope this helps. Good luck with your search!