Stencils: Cookie stencils of all sorts are available on Amazon, but the best stencil tool is the Stencil Genie
Airbrush: KopyKake Airmaster
Airbrush Colors: Americolor AmeriMist set
Frosting Printer: Inkedibles is the go-to for these (this probably goes without saying, but do not EVER use it for anything other than food coloring). I have the Canon.
Edible Paper: Inkedibles frosting sheets
Edible Ink: Inkedibles ink
Icing Smoothing Device: The Frostinator by Evil Cake Genius