You can purchase it at some of the head shops over in PCB. You just have to inquire about whipped cream cartridges. Call it whippets and they'll ask you to leave.
When you buy whipped cream in the can shake it in the store. It should go from a sloshing sound to a flopping sound. If it doesn't firm up in the can when shaking then someone has already stolen the nitrous. Nothing like getting home and having heavy cream dribble out onto pie.
Your depth of knowledge is both impressive and faschinating.
