Do you have nothing at all ? Or you have a Weber kettle or other and want accessories? If you have no smoker them it's:
Weber Kettle or Brinkmann Gourmet( u will have to do a cpl easy mods) or a Big Poppas Drum Kit ($139).
If u have a smoker and need extras then:
ThermoWorks Meat Thermo ($19-$24 Amazon), Good Tongs and Meat Fork, Charcoal Chimney, Cpl of Stainless Steel Pans, Hot Gloves ( maybe Welders gloves), Various Rubs, Grate Brush, Injector Needle...