We got our first carseat put in by an RACV accredited installer (the local mechanic) and it cost $70. $30 for actual install and $40 for some extender strap because we have a hatchback, later found out they're about $25 at Kmart but I was in hospital with a newborn, DH didn't have a clue and was in a hurry to get it done so he could pick us up and take us home! DH put the carseat for our other car in by himself and got it checked by a mechanic.

If you don't have your car manual handy (I know I don't!) you could probably find it on the net....that will definitely show you where they are. I doubt a 98 model car wouldn't have one.