The Cash and Carry across town has singles with a different print: the 96oz ones for about $3.50, and the bigger ones for $5. So there is a better supplier...
I got that email from BaristaWorks, but there was another place that used to sell these at CoffeeFest (Joe To Go?), I'll have to dig out my notes. Personally, I would preferentially use 32oz styrofoam cups (with the styrofoam lids) with a four cup holder, as they are better insulated and much cheaper - less than a buck a gallon.
[Green Solution] Talk people into bringing their own airpots, or charge a premium to use yours. I've only lost one airpot in over two years.