TIG backside purging advice?

[funcars]

After doing some stainless exhaust welding without back purging I know I need it for the next effort. Would probably be very good for aluminum tubes as well. Doesn't seem to make as much difference for mild steel. I don't want to invest a ton of dough, but I need something functional. I do have an extra flow regulator/meter if that helps. Ideally I would like to have the flow turned on and off by the welder. One other issue is that I am constantly turning and moving the tubes to get torch access so the faster and easier to connect (or rotate without disconnecting) the better.

Any ideas, pictures or links I could check?

Thanks