I've got a $1 knife in my fire kit, BUT

-I use it primarily as a scraper for my ferro rod
-it's secondary use it to pry pine pitch off of trees
-it's third use is making wood shavings

Granted, mine is tiny, but I have a hard time accepting anyone who tells me it or one of it's family members are good for much more than that. I use my tiny cheap knife to save my good knife for the big jobs. I want something of much better quality if I'm going to be splitting wood with it, for example. My knife is something that needs to take a beating. Mine aren't high end but they're tough enough and I know I can trust them if I keep them sharp. The problem with a poor knife suggestion is that it can result in injury, especially in an emergency situation.

I am a fan of the space blanket, as it's good for shelter and first aid, but I have upgraded all of mine to Heat sheets because the standard Mylar blanket is just too fragile. That said, I really like disposable ponchos for emergency kits. I keep a couple in my purse and all my kits, and I'd pick it over a Mylar blanket or bin liner in a heartbeat - especially if someone wasn't familiar with shelter building. They're just more user friendly. They're one of first things I throw in my kiddo's kits and suggest to my Scouts and their parents. Shelter from the elements that they know how to use - The KISS theory in action.