I've got the cheap ones off the auction site, as everyone says they have no electrical contacts so the aperture at its widest, and force you to use manual focus. They do allow you to focus ridiculously close to things, but it's difficult with insects (my favourite macro subject) which are constantly moving. With this and such a shallow depth of field, it sometimes feels like a game of chance managing to get a decent photo.
I've actually been using mine about 5 minutes ago before I saw this thread, I'll check out my pictures and see how good they were.
