They're only about £100 from your local Toyota dealer - so just pick them up from there and use your Gold discount...
Also in order to make sure it is the Ball joints, jack the front of the car up, and then check for play by grabbing the outer part of the rim and moving it up/down/side to side...should tell you if the ball joints are knackered...another sign is a slight "clicking" sound when you reverse whilst parallel parking on the side of a road or onto a drive with a slope.
Hope that helps. Also brake discs don't warp THAT easily! I've got a set of not so good EBC discs on the fronts and although the discs have been punished like no other (multiple *55mph* stops), and brake fade kicking in, I've not had them warp on me yet.
Unless you do that sort of thing EVERY DAY then it's another matter or if you're into tracking your car

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Anyways, I'd get the balljoints checked out first then everything else

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PS: If you get your balljoints done, make sure you get a good mechanic to do it so the alignment/tracking can still be "retained"...otherwise get the car aligned/tracked again

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