P30sk 13r Mag Floorplate

Mine somehow broke yesterday, while doing a class. This is the extended, 13r mag with the sleeve.
HK is out of them ($7). I found one @ Midwest Industries, but it was $21...! WTF?
Does anyone know of another independent supplier who might have these?

Attachment 50878
Attachment 50879

Mod, I Created another thread in the pistol section, where it should have gone; please delete this one.