Have you already asked the Southwest Seattle Historical Society?
Also the Seattle Municipal Archives. Though most of their old images are for obvious reasons focused on public-works projects/problems, you sometimes can catch structures and street scenes.
We lived in the 3700 block of Beach Drive our first two years here, 1991-1993, and there was still an old mini-mart right across the street, where Cormorant Cove Park is now. I remember buying dusty packs of bubble gum and cans of emergency cat food there. – TR