Hello and welcome! Not wonderful news on the A3 camera I'm afraid - it's not worth much. I would say £10 would be fair. You could price it at £15 and see how it goes. Does it have a lens attached to the camera? What is that lens?
Re the additional 80-200mm lens, we really need to know the full text written around the front of the lens. For example the text on the lens below that says 'SMC PENTAX-M zoom 1:3.5 28mm - 1:4 50mm'
It is likely that the 80-200mm lens is a Pentax-M or off-brand lens worth only about £20 but you never know!