My 1962 MGA sports car car has an OEM repro banjo steering wheel that I purchsed from Moss Motors in Calif. decades ago. When I bought the car it had tired old wood-rimmed job from Pep Boys or JC Whitney. I forget what I paid for it all of those years ago, but Moss still offers the same repro wheel today for $290.00. They will also sell you a classic Brooklands-style banjo wheel for about $630.00.
You Tube has lots of steering wheel restoration vids. I like this one that shows the creation from scratch of a banjo steering wheel for a 1935 Cadillac. It looks like a fun project, but the equipment and chemicals are very expensive for a one-off item.