Interesting comments about Airgas. As an OEM for both TD and Hypertherm, we get our plasma consumables directly from the manufacturer, but for everything else, we are lucky enough to be in a large population area with 5 or 6 welding supply houses and competition keeps them in line. The one we deal with is a family owned business where if there is an issue, you can knock on the owners door.
Regarding Airgas and Praxair...If you need a regular supply of consumables, they are usually eager to accommodate. Many of them use these plasma machines as loss leaders because they know that if the treat you right on the plasma, you'll be back for consumables. Sometimes you just need to get to the right person and explain that you only want to deal with one supplier and if you have to take your consumable business elsewhere everything else will go with it. Someone other the hourly counter guy needs t know that if you have to wait 2-3 days for consumables, you'll just order them online.
Our industrial customers seem very pleased with both Airgas and Praxair, but some of them spend in excess of $1000/month on consumables and that may have some bearing on what they stock. On the other hand....Airgas is VERY pro Hypertherm and we've found that they usually try to keep a decent supply of consumables.