In the same boat with needing the components changed, but I do not think that I will be lowering my camry.
The suspension is near due, and the swaybars, bushings, control arm bushings are waiting arrival from the whiteline group buy.
What model do you have? 4cyl? and what size rims?
The front disc caliper upgrade will only work with 15" and larger rims.
My front brake job cost $230 for 2 rotors (brembo) and pads.
An upgrade for larger discs will include 1
pr calipers, one pair torque plates, rotors
pr, pads, 1 set. That would add up to 350 there.
I would suggest you leave the drum to disc conversion last. you will need time to gather the parts and a bit more money. You will need an alignment after.