There are a lot of bushes in the car and it is probably not worth changing them all.
In the rear on each side there is the lower control arm, and the two upper arms, thats 4 bushes a side. There is also 2 in the hub but i normally dont change these unless it is a race car.
In the front there is the one in the caster rod, the ones in the front camber adjusters and the lower arm. The caster rod one is the one that most needs changing, the others are not as important.
I would start by changing the caster rod and the rear suspension arms and some rear subframe rings. The parts will cost about $300 and im guessing about $200 for fitting plus a wheel align.