do any of the supporting vendors sell this oil drain plug

Here is the list. Many good vendors here and yes many of them sell the valve. http://www.dieselplace.com/forum/showvendors.php?

I know for a fact that Huckstorf Diesel sells them. You can find their info at www.hdiesel.com (http://www.hdiesel.com) . I don't think that it shows them on their website but I know they have them cause that is where I got mine. Just give Mark or John a call.

I bought mine from Kennedy Diesel along with my AMSOIL products and oil and fuel filter.

Eric at Merchant Automotive carries them as well.:)