for 1.5~1.6L cars, it's about 65~80 buxx per weekday, weekend charges are higher. the price u are paying daily already factors in the insurance cost. but keep in mind that petrol u have to pay urself. ie to say, they hand over the car to u with fulltank petrol, you have to return to them fulltank petrol also. if not they'll charge u for topping up their rental car.
Most rental packages include insurance but the basic rate comes with a rather high deductible, usually about $1000. So if any damage, you are liable for the first $1000. I recently rented a Honda Jazz for $250 +gst for the weekend, from Kah Motor Rental. They give pretty new models.
There's also an extra charge if you want to drive up to Malaysia.
Why don't you just call the rental companies to find out? They're probably the best source of information I would imagine.