Here is another product that turns your charcoal kettle grill into a smoker. The Slow n Sear Plus 2.0 can be used in a 22″ grill you own already. It comes with a removable water reservoir, which provides over 5 hours of moisture.
The Slow n Sear Plus 2.0 is made from 16-gauge 430 stainless steel. You can get yours for under $100 at this time.