I don’t know if this is common knowledge but you can buy K-shank needles from China for under a penny a piece. They are actually sterile acupuncture needles. The only thing is the minimum size is .006 (.16mm) with a minimum length of 7mm. They work fine for me though.
https://item.taobao.com/item.htm?spm=a1z0d.6639537.1997196601.168.18fd7484Pbg3cp&id=547035098824
A packet of 500 cost $4.80.
What kind of metal are they made from?
This is what I get when I run the verbiage through Google Translate…
" Material **quality: a needle body and a needle shank made of medical stainless steel by high. Yunlong brand facial ear special acupuncture needle, disposable aseptic packaging, suitable for facial wrinkles, freckle and acne cleansing, can also be used for acupuncture and moxibustion."
Not really sure what moxibustion is but they appear to be high quality and work exactly like “regular” needles (probes)