Customs 49 Buick Porthole Question

My 49 Buick has porthole "covers" on it that are really neat. We're these a dealer installed option? Where can I buy new ones? I know it will be expensive to replace these.

 

Aftermarket, there was a few different designs. I think I have 5 of the same ones.

 

Stock looks best imho. There were domed screens that did look good that popped into them.