Inline Tube

Classic Tube

Also, many of the reproduction parts vendors sell sets from one of the above manufacturers (you can, of course, buy direct).

I have bought a few sets from Inline Tube and they fit very well. If you want to bend your own, buy the bulk stainless steel tube. I think you need a specialty tube-beeding tool to work with the double flare on a stainless-steel tube (someone who has done this will post better information).