THIS SHOULD BE UPDATED TO REFLECT THE CURRENT YEAR, IT HAS BEEN ARCHIVED
PenguiCon's sister convention, LinuCon in Texas, has had great success making ice cream with Liquid Nitrogen in their ConSuite. RobLandley, Molly, and JenniferSkwarski made this in the ConSuite at PenguiCon in 2006.
The liquid nitrogen came to $220, although I think that's because I ordered the wrong tank. (The 3000 psi tank is cheaper than the 22 psi tank, because it's easier for them to fill from their big high-pressure tank.) It should have been somewhere in the $125-150 range if we get the right kind of tank. 180 liters seems to be exactly enough for the weekend.
Oh yeah, Penguicon will want to have its own cryogenic transfer hose, and a phase separator. Hoses are here: http://www.airgas.com/browse/product_list.aspx?catID=167
I thought we had a 6 foot hose, but it might only be 4 feet. (Mark said it was about $150, that sounds like the 4 foot one.) I'll ask him to measure it…
It'll also need a phase separator: http://www.airgas.com/browse/product.aspx?Msg=RecID&recIds=28661&WT.svl=28661
Those should be one time expenditures, not annual. (Although the phase separator is delicate when it's cold; we managed to shatter one by dropping the hose and letting it whack against the side of the tank after a fill. The second's a couple years old now, though, and seems to be holding up fine.)