Up for sale is a 1st generation Riviera wood steering wheel and center horn cap- Looking to get $950 Has very minor pitting and very small cracks where the bars meet the wheel. No bends. No horn bar. VERY good shape overall. Have more pictures on request. Located in Northern California (Ukiah - 95482) Pick up preferred but willing to ship within continental U.S. on buyer's $.
You should try posting on the Riviera forum, wood wheels generally sell pretty quickly there. https://forums.aaca.org/forum/73-buick-riviera/
Sorry, I decided to pass -- didn't know procuring a m horn bar would be an expensive propsition on its own. Good luck with the sale.