mate my dad had an abs module problem. the instrument cluster would light up like a xmas tree everytime you started her up, the abs and traction control wouldnt work and funny enough the air con as well. We asked around for prices to get it fixed. it was about the same everywhere give or take $10. We ended get it done at holden as the price was quite competitive. $560 from memory. dont quote me on that. That was for a refurbished ABS module. a new one would have cost and arm and leg. 3 yrs on and everythings fine.. no problems at all.
thats something thats not solid, these faults can range from many things from the Chips to resistors to the electrical channels, its hard to say what the fault is exactly without diagnostic equipment or patients to test every little conductor, resister, chip pin, and check the actual circuit board for damage.