This topic has been covered a couple times, so feel free to search around.
More info is nice too, like 2WD or 4x4.
You'll need a transmission (4x4 or 2WD M5OD for the 3.0, no other transmission will bolt to the 3.0), flywheel, clutch kit, master and slave cylinder, manual transmission pedal bracket, manual transmission floor plate, manual transmission wiring subharness (or you can keep the auto and splice things like I did), and time.
Price these things out and it will give you a base cost. How hard it is depends on your mechanical ability.