Im not convinced on the brakes being the problem.
If the wobble is always there then its normally an out of shape tyre somewhere. If the wobble is reduced or you can drive through it at higher speed then normally its just the balancing. If the car seems to crab about the road then i would check bushes and tracking.
If these dont solve the prob, just to investigate the prob further swap your front wheels and tyres to the back and see if that makes a diff. If it doesn't then swap if not rotational tyres from side to side and see if that makes any difference.
Normally in my experience warped brakes would only be noticed when you brake, not whilst your driving as normal.
Worst case scenario id check the chassis to ensure the car wasn't in a little bump before you got it.
How long have you had the car? How long has this problem been around? Did you have this problem before any of the bushes / suspension changes? If not then id associate the problem with one of them.
Ant.