The whole visor assembly is pricy from any of the sources I've found--but it sounds like you need only the clip that mounts into the windshield header trim, and can be removed from same by removing the one screw through its center. That can't be that expensive; might try checking the dealer, K&K, benzbin, etc.
'97 SL500, 40th anniversary edition
'04 Olds Bravada (SWMBO's)
'06 Lexus ES330
'89 560SL (sold)
SL--Anything else is just a Mercedes.
(Kudos to whoever said it first)