How or where can I find donated stair lifts?

This is an international forum, so it isn't likely you'll be able to find help here. A stair lift is particular to your staircase, so someone can't really just give you one and you can install it. The tracks come in segments, and you need the right ones for your situation. You can't easily install them yourself either.

We bought a used stair lift for my mother from an authorized dealer, then sold it back to them once she was moved out of the house.

Try contacting an Acorn Stairlift dealer or a medical equipment supply store in your area.

The problem is this is a Caregiver forum. We are mostly from all over the US, Canada and the UK. Would be hard to find someone who would live near you that has a a used stair lift. They are usually custom built for the staircase they r being used for.