Hi,
I know in Scotland (not England) houses tend to sell for 10 to 30 per cent over the asking price. Whereas cars sell for less.
Aircraft also sell for less, but how much less also depends on how they have been priced.
In microlights, I tell students that vendors will be happy with a 10 per cent cut - but then 10 per cent of a 50k microlight is 5k and that can seem quite a bit!
There again, a 3,500 microlight might sell for just 2,500, maybe even 2,000 if it was well over-priced and has hung around for a while - and that is a whopping percentage discount.
It also depends on the model, condition, colour scheme etc etc.
You are doing the right thing by asking around.