To make more of what I made before runs about $40 for 5 gallons, which is worth about 2 cases (48 12oz bottles) and change. Cost of the class was $15/person (with all funds going to TCMaker) wasn't it, Karin? If the group wanted to pitch in for the kit though, I'd be more than happy to just show up at the space and make the beer and if anyone wanted to stop in, I'd just do an impromptu thing. It would be great to make the recipe again, as there seems to be an efficiency hole somewhere in my process, and the best way to find it is to make the same beer multiple times.
The shelf life of a corny: The keg itself or the beer inside? The keg is as long as it holds pressure. Every so often, you need to replace the rubber components, but the rest is stainless, so quite a long time. The beer inside, if it's kept cold and free from ambient air (needs inert gas like CO2 to prevent oxidization of the beer) it will keep fresh for many months.