Try the usual suspects. I’ve replaced my passenger side whiskers earlier this summer. You can find them at Authentic Classics, Buds Benz, Palm Beach Classics, vintage Euro, Miller’s, probably others. The original Mercedes OEM are NOLA. Everything out there now are repro’s, they are still fine but thinner than the original. If anyone knows where there are OEM’s in stock, please update.
The sunvisors are pricy and the quality varies greatly with price. MB original visors are over $600 each. There are some cheap repros around $200 but are very flimsy. I know, I’ve bought 4 different visors this summer and returned 3 of them due to quality and color issues. Buy them as a pair if you want to ensure color match.
I see this is your first post, welcome to the group! My 280SL currently lives in Canada with me, but it was originally delivered new in Fresno.