It depends on what is the problem. Mine, the car exhaust was detached from car and dropped to the ground. So what the mechanic did was weld it back to its position and tie it up with a rubber. That cost us RM40. He did advise to tie it up using spring so that the exhaust can vibrate. That will cost us another RM100. Since we don't have much money to spend, I told him next time when we have extra cash.
Next is to change the electric injection on my car. I wonder how much it will cost. :(