I'm glad I read this thread! I have some cheap cogs, and I'll use them, but I'll stop buying them, too.

A friend of mine did once bring me his wheel and asked me to get his cog off. It was very difficult to remove. I had to abuse it to take it off. The lockring was Dura Ace, and since it was made of very high quality steel, I barely damaged it. So that's a good word for Dura ace.

carleton, a couple of years ago, a bike of mine was stolen. In my toolbag hanging from my saddle was the peanut butter wrench. Miraculously, I recovered the bike three months later, but the tool bag and its contents were gone. The prices on those wrenches are too high for me. A car mechanic friend of mine made one for me. He used a Craftsman combination wrench and welded a 15mm socket to one end. Just for kicks, he welded a very large bearing ball to the other end.