My Argon costs $16.43 /100cf
So my 280 CF tank costs $59.13 with tax and Haz mat fee.
Key Largo, FL Mathesion Tri-Gas, Miami, and TX

I maybe wrong but Argon is the 3rd gas in the AIR. At .0.93%. So it must take a while to extract it, hence the cost.

Thanks,
Gary