Left lower control arm??? Dealer quote...

[Rado]

I went to the dealer today for a simple headlight aiming adjustment because I put new depo headlights and thought it would be nice if they do it to their specs instead of me messing around. Anyway, they adjusted them fine but told me that my front left control arm is loose and needs a new one soon and quoted me $550... Is that normal?.. I have no idea how much it should be, I will most definitely check with indy shop but wanted to see your opinion.
I don't know why they would even check this kind of staff - I went there for completely different service.
Any help would be appreciated.
I have 2001 X5, 3.0L, sports/premium package