I think the market is limited. It might probably appeal to some hot rod enthusiasts but I personally would not buy one. Plus the price would be probably quite a bit higher since that lid would be way more expensive to produce. But you can always get some masking tape and high heat yellow paint and try a DIY job. Or get a paint job done by a professional.
Weber has done a lot of custom lids on the Q grills and I don't think they do too well. They have to make enough of them to make the production of them worth while, but then they have to balance that with the limited market for them. If they produce a Chicago Bears grill, it will not sell well outside the Illinois area. If they make a generic custom lid, it might sell across the country, but since the price is higher, it won't sell nearly as well as the basic colors due to price and the gaudiness of it. I have seen a lot of the custom grills being sold on sale at stores due to over stocking them.