It probably would not cost to much to have that made at your local machine shop. It also could be made from many different type metal if wanted (brass,bronze,cast iron, or even 6061 or 7075 aluminum).
Also a quick fix could be to get your local welding shop to braze the pieces back together. You might have a small problem with weld coming through to the threads inside but if it does just grind that small part out with a die grinder because you have plenty of other threads ( this is not permanent right). Welding would not hold as good as brazing here so be sure its someone who has a big torch.
Someone may have one that doesnt need it, but with backorderes at grizzly and the very thin cross section of the part they may all be gone from others needing them.
Jess
GOD Bless, and prayers for all.