The bracket I use most often is the spokes that are on the steering wheel itself. I drill a hole in one that lines up with where I like my hand to be and use a double nut to lock it in place. If you have no flat spokes on yours, then a U-bolt holding a piece of aluminum on a spoke with a hole in it for your button may also be an economical choice that you can make to fit your steering wheel better than a generic bracket purchase?
Bruce