> Does anyone know where to get small cylinders of nitrogen
> or argon gas to use in food preserving? ...

As Bob asked, will CO2 work? That's pretty widely available. However,
for the others, check your Yellow Pages under "Gas-industrial & Medical
Cylinder & Bulk" (in my area). There's a company around here called
"AirGas" that does most everything and I got CO2 from. You have to buy
the first tank and fill, then you can swap it for refills and just pay
for the fill.

You'll have to also buy a regulator, hoses, etc. You can get complete
CO2 setups from most all homebrew beer shops (like:
www.williamsbrewing.com or www.morebeer.com) under the "Kegging"
sections..

Derric