Here's one of the two listed as NOS, reasonable price. Finding both 3892281 (LH) and 3892282 (RH) as a pair is possible, although they are pricey. Otherwise, options are obviously reproductions or used originals, or find a good shop and replate your originals.
I think OER is the only brand on the market right now and they are back-ordered. You would need to find a vendor that happens to still have some.
They were still available from GM for sometime, so NOS ones are usually not that hard to find. Often some up on eBay, but be careful there. There was a large batch of unpainted "seconds" that were being sold as NOS out of Michigan a few years ago. I saw some and they were rough. Not even sure they were GM. I was told the guy had a sizable quantity, so they could still be floating around.