Originally Posted by just_nuke_em
Today praxair quoted me ~$2 and airgas quoted me $4. Where the hell in the US do you guys live that you get it so low? If I could get it for <$1 I would fill it up every weekend and use 120L per month.
I go to the Raleigh, NC Airgas and get it at $0.50/L. I did it by showing reciepts from a friend of mine in OH (different Airgas region). Print these...
...and take them in with you to Airgas to see if they'll match the price. My Airgas started at $6.00/L. I talked them down to $1.00/L but needed the receipts to get the $0.50/L price. They literally had never heard of it being sold that cheap. Once you show them it is, in fact, done (and assuming they are nice like the folks at my Airgas), they have no problem matching it.
As for how much it costs (and I'm spitballing here, this is not something I know for sure), the LN2 is relatively inexpensive because it's a byproduct. Wiki says
you make LN2 by fractional distillation of liquid air. There are other, more expensive, products produced in that fractional distillation, such as helium and oxygen.
Since they're separating the air anyway, it doesn't cost much more to grab the nitrogen at its fractional spot in the distillation process. Sure, the initial investment is high but the goal is those more expensive and more widely used gasses (well, liquids). That's my random guess as to how LN2 can be relatively "cheap" to make.