A quick web search found some suppliers other than 3 Rivers who still list JoJan products for sale, including the big auction site whose name must not be mentioned here. JoJan's closing must be fairly recent, because this is the first I’ve heard of it, so I would imagine there is still some product out there.
Unless you're committed to right wing, consider using left wing as well, in case right wing is hard to find. Just don't mix the two when you make arrows. Also consider straight, as recent studies indicate that straight works as well as helical, maybe better, although these studies are fairly recent and may be challenged as time goes on.
Moderators may want to move this post to PowWow, as there may be people who post there who have the clamps he is looking for who may be willing to part with them.