A new Utility shed found under Storage / MiscStorage, costs 0. It's purely a décor item. For CAW, found under Metadata / Game Objects / Environment in CAW. You need Supernatural or a later pack and to place the package in both the "Electronic Arts / The Sims3 / Mods / Packages" directory and in the "Program Files(x86) / Electronic Arts / The Sims 3 Create a World Tool / Packages" directory for the shed to show in your game. There is an earlier post explaining how to install items in CAW.
Importing packages into CAW
Tool Shed ( CAW optional )