The camera usually comes with the trail camera setup if you buy a retail unit. But you can also buy a kit that gives you all the components to build a trail camera setup w/o the camerabut it requires you to takeyour camera apart and wire it for external triggering. This is known as a homebrew. Some of the suppliers of the kits are
www.pixcontroller.com and
www.whitetailsupply.com/XLP-Package.html