It should be easy for the shop to confirm warped discs. That would be my next move.

EDIT: Oops, just went right over how a simple diagnosis is expensive there. That's crazy. My shop won't charge me just to inspect the rotors.

When I had my control arms replaced I had the ball joints done too. However mine were confirmed needing replacement.

18 months into ownership I had this done to the X.

(Actual prices charged)
2 Front lower control arms ($292)
Replace both control arms ($179)
2 Ball joints ($55 each)
2 Control Arm Bushings ($104)
2 CV boot kits ($73)
Replace Outer Boots ($269)
Wheel Alignment ($79)
Cabin Filter ($33)
Oil Filter Kit ($13)
Mobil 1 Oil ($56)
Oil Change ($20)
Total parts = $683
Total labor = $547 (I think they mentioned at least 6 hours to do all the work)
Shop Supplies, Tax, Etc = $83
Grand Total = $1,310