According to the data sheet this camera requires 12 VDC +/- 10% or 48V POE Power over Ethernet which is typically provide by a Ethernet Switch with POE capability or a POE Injector in line with the Ethernet cable. If you use the POE Switch you do not need a separate power supply. If you choose to go separate power supply a 12VDC > 5 watt power supply is easy to online or at places like Radio Shack
If you are using it with WiFi, the least expensive is a 12V wall wort adapter with a 2.1mm connector which is pretty standard. I don't use WiFi with mine, so it's powered via the Ethernet cable that connects it.