Steering the topic back, I cannot say that I collect in quantity anything in particular; I use ebay like a car-boot sale.
I tend to get old radios - 1930 to maybe 1970, radio test equipment, the occasional clock, the occasional pressure stove or lantern. Nothing of too high a value - too risky unless I can either see it or specify exactly what pics to send me.
A typical bunch of things I recently sold:
A wine filter
Some vintage car magazines
Part of an old car radio
I have recently bought:
A Fitzroy barometer
A radiogram
I am looking for:
A coil winder
A 1950s/60s Goblin Teasmade
I am going to sell shortly:
A Metz camera studio flash
Couple of Russian cameras
A load of camera bits and cannibalized cameras
A Lanchester 'driver's instruction card'
Ho hum.....