One could try the bathroom fixtures section or kitchen suply. All they are is a towel rack. You may luck out and find the tubing there but i haven't seen the stands. Since Gambles went out of busnesses.
Maybe marine supply houses might have something maybe? I have a bout 15-20 of these but only ends, no middle or angled though. Thinking maybe flower car on these maybe but could have been a cabinet rail mount too for something.
If you have some in poor condition I suggest you send them to Speed & Sport Chrome in Houston, Texas and Craig will make them new again. His specialty is small parts. I have used for gas pump and coke machine parts and most recently for railings on a flower car.