Beware of Chinese made tubing. You will see some places sell 4130 and DOM way cheaper then the next guy. More then likely the cheaper tubing is made in China. The China made tubing does not have the consistency nor strength as US made tubing, however it is cheaper.
Make sure you ask what the country of origin is. Do not except 'I dont know' because they do (*or should).
Kiwi, if you are in the Portland area and need tube send me a PM. I buy a surprising amount of structural steel and have someone on the inside that can get you what you want at very reasonable prices and can tell you where it comes from.
~JH