Given the choice, the Life hammer is my first grab, but the ResQMe is graet because its in my pocket all the time.
I was going to say that I got mine from eBay, but gp_frk has bet me to it.
Another use for the Life Hammer over here is the companies that supply cargo barriers for wagons. They supply a Life Hammer attached to the barrier in the cargo area. That way if the back door is closed and if there is no inside handle, there is still a way out.
There was a child killed some years ago because his brother slammed the back shut and ran off leaving him trapped in the summer heat with no escape, and this was one of the responses to the prob.