1997 Pontiac Sunfire Noises

I heard a clicking sound when I hit my brakes backing up and going forward. I took it to the mechanic. They said I need new rotors and pads, and then about 10 minutes later they say I need a new axle. They showed me the passenger side axle and I saw that it had a lot of goop and grease on it. They said if I didn't replace it then it would eventually break. Does that sound fishy or legite. Help me out please, becasue I paid 300 dollars for all of the above repairs.