I think I still have a black outboard numpad with white Alps switches, but I never used it because it has a peculiar plug that looks like a headphone jack, but smaller. Like the size of the old micro-cassette dictation recorders with the smaller (maybe it was 3/32" instead of 1/8"?) plug.
I would sell it cheap if somebody knew how to hook it up via USB.
edit: sold to spam ray