Hard to say, it's not available yet and they haven't determined what the price will be. It is going to be compatible with the Weber 18 1/2 kettle grill. Just have to wait and see.
It's like everything else, you don't need it, you want it. Just another BBQ toy.
Treasurer, Great Lakes BBQAssociation
Rubbed, Smoked, and Sauced Competition BBQ Team-
22 1/2" WSM, 2 18 1/2" WSM's, 22 1/2" Weber Kettle