There’s standard pricing for cars now that all garages use for valuation. You can get it free online with folk like auto trader or confused.com
That’ll tell you the real market rate for your car and mileage. Better to base it off that then what other cars are being sold for.
I’ve used ‘we buy any car’ before and got a decent price but they will mark you down for any damage at all so it’s often not worth it if your cars in a bit of a state |