1986 Saab 900 S

I recently acquired one of these for free.

I use it as basic transportation, but would like to replace little things at first, like the dashboard, the factory radio etc. These things have damage.

Where is the best place to find used parts for the interior parts such as these..

Also sooner or later I will want to replace some minor exterior things like headlight casing and trim.

Thanks for the help.