I'll be the one to say that I haven't had any medications on hand in nearly 10 years. Not saying that's the right way to go, though. I guess I don't add new stock too often, and when I do (including LFS, local breeders, online retailers, and eBay), I've just been lucky. I don't even keep a quarantine tank, though I suppose I could have one set up fairly quickly in a pinch.
I last had to treat for Ich in about 2007, when I was just getting started, and I think I just raised the temp and aerated for a couple of weeks until it ran its course. Could have done it faster with meds, of course. No other obvious ailments have affected my fish or shrimp that weren't related to water quality (I used to lose inverts until I got my hardness straightened out). I don't even have any snails or algae of unknown origin.
So, I'm just going to brag about that and hope to keep the streak alive. If I ever needed something, I could get it pretty quickly, but it's certainly better to have the basics on hand in an emergency.