He costs $3 per m^3 on the open market. Argon costs about $8 per m^3. N2 is cheaper. There are some uses for He that are harder to replace. Argon will collect

He costs $3 per m^3 on the open market. Argon costs about $8 per m^3. N2 is cheaper. There are some uses for He that are harder to replace. Argon will collect in low spaces more than He; N2 might be a compromise for welding. Nothing can be relied on to be quite as cold as liquid He. But there is a lot of substitution that can be done when He prices rise, several generations from now.