A real good read daics.

I know Dogswamp really well, was there day before Xmas, but alas aforementioned pinballs now long gone, hopefully one day return
I remember driving up Wanneroo road in the 70s and every chip shop, burger bar, deli and pizza shop had at least one pinball and a Spacies cocktail.

I think $1500 for Bally SI sounds reasonable, you should be able to get one for that. I know they are not very common but shouldn't be impossible to find.