As of 2015, argon gas can be bought online from retailer PraxAir, as well as from the website of industrial gas supplier AirGas, and from the web store at Harbor Freight Tools. Argon gas has a number of useful applications, especially in welding and metal working.
PraxAir's web store features compressed argon gas in a number of different purities and concentrations. They sell 99.998% pure compressed argon, argon mixed with helium and argon mixed with hydrogen. They also sell liquid argon.
The web store for AirGas offers high pressure argon cylinders as single units or in bulk. They also offer a service to welders, called Welding Efficiency Analysis, that claims to maximize argon supplies at work sites.
Harbor Gas also sells argon gas cylinders at its online store. As of October of 2015, one argon gas cylinder at Harbor Freight costs $89.99. Harbor Gas markets its argon toward welders.