Buzzing noise coming from rear right wheel/tire.

I have a buzzing noise coming from the rear right wheel of my audi a4 1.8t quattro. I took it to tires plus and they said that the wheel bearings needed replacement. I just want to make sure its nothing else like a brake or router problem that i can fix myself before spending money on it. Becasue i do have the abs light on as well.

Basically the wheel makes a loud buzzing noise and its getting louder now ..but only when the car is in motion.
Does anyone know what is the problem? and how much it costs?

help please!