So I've been doing a little research, to help those of you who want to destroy your eyesight.
There is very little to be found on the internets about these antique knitting pins! And there are even fewer sources for knitting pins, if you were to want to buy some.
Since I have no intention of re-doing what has already been done well, I offer you summaries of History of metallurgy, knitting, and steel in Julie's first summary and its continuation, and even more on knitting needles and their spread. Go on and read them, I'll wait.
So now you know why we're so interested in these funny, skinny, steel knitting needles. They're pretty useful in helping to trace the migration of knitting across Europe and Asia, even if no one can yet decide by which path they travelled (my guess? both.).
Now all you re-enactors out there might want to give this a try. A quick search of EBay shows me that today, at least, there are not many surfacing from attics and whatnot. I found mine in a fairly isolated antique store standing in a cup with a bunch of microscopic crochet hooks (I bought those, too, but they're another post of their own) for a dime a piece. I wasn't a huge knitter then, but recognized the once-in-a-lifetime opportunity and took it. I think I spent a little under $4 that day.
Then where are you going to get them?
Wooded Hamlet Designs carries some, but not all, of the sizes a re-enactor might desire. I have purchased from the in the past, and everything is of high quality. This is a good place to keep in mind when looking for "lost needlearts" supplies.
Nordic Needle has a variety of forms of small needles, like single-point, double-point, as well as a bizarre collection of other things you may or may not find interesting. (Nordic Needle sells coffee??) I've never purchased from them, but they do carry smaller needles.
Lacis is a well-known and reputable source for needlework supplies, and they happen to carry smaller knitting needles, too. Their catalog is one of those publications that in my house gets dog-eared and read like a magazine!
And if you're just hungering for a place to start, and maybe compare, try here. They have four versions of a vintage sock pattern: one is original, one is a modern redaction, another is modified for a larger gauge, and one is modified for worsted weight for a new sock knitter!
And last but not least, I offer BugKnits. That woman is amazing, and sells her itty-bitty teeny-weeny needles to the public. How about 00000000000? Eleven zeroes! She focuses on miniatures knitting, but her needles (scroll down to the bottom of the page) could be quite useful for a re-enactor who wants their soul sucked out while knitting knee-high stockings on 0.5mm needles at 22 sts/in.
If I missed a source you know of, please let me know and I'll add it to the list. I would love to have a complete list of sources for re-enactor knitting needles.
And remember: magnification glasses are not just for failing eyesight! They can be wonderful when working with these tiny little stitches!!