Source for used or surplus sealed keyboards?

Have had some interesting moments when trying to stop my Ahha fitted
knee mill, only to find a chip has worked it's way under the key,
preventing a full stroke. I've checked a couple surplus catalogs I have,
don't see any. I have seen keyboards that look normal, but are sealed to
liquids and debris. I'd prefer one of these to a membrane, but would
take a membrane over another chip under the escape key!
Anyone have any ideas where I might find one, or have an extra laying
around?

Thanks,

Jon