I picked up a used Weber ring a month or so ago, and have used it 3 or 4 times. There is a gap of 1/8" to 1/4" around about half of the bowl, but I just fill in the gap with folded pieces of aluminum foil. Not the tightest fit or the most controlled cooks, but it works just fine for me. I've done some chickens, a great chuck roast, and even a whole ham.
If I was a lottery winner, I'd prolly buy a new CB ring, but those never come up on CL, so this $50 device is just fine by me. Can't wait to do some more rotis cooks in the new year.