I also think that your seller should make things right (though you should remember that there's sort of a statute of limitiations on things like this - you may need to contact them
soon.)
But if you do end up taking care of it yourself, I know that buymilsurp.com has a lot of used cz 82 parts for pretty reasonable prices. Can't say if it's exactly what you'd need, but they've got safety parts for only $18.00.
Automatic Safety CZ-82I've never bought anything from them, so I can't say anything more about the company except that that's a lot better looking number than the $69 you cited.
Good luck, once you get this resolved you're going to have a great gun that will make it all worthwhile!
C.C.
EDIT: I looked a little closer, and I guess that's probably NOT the part you'd need after all. Maybe this one? No pictures - very frustrating...
Safety Czech CZ-82