You need to ring the EA and say you have an interest in the property but your research indicates it's significantly overpriced. Give examples of recent sales.
Then ask why they believe the house merits the current asking price.
Make a decision based on that information.
Of course the price might be vastly inflated.
Some sellers haven't got used to the falling market, sometimes people list at a high price just in case they get lucky but aren't under pressure to move, sometimes there are messy family circumstances where a price is inflated deliberately to stop it from selling.
Or there may be very valid reasons you are not aware of.
For example I live in a village that is spilt in two by a river bridge. The larger part has the period properties, school, doctors, shops, pub and all the village amenities. The other is mainly more modern housing and you'd face a pretty stiff walk in winter on the school run for example and in rush hour the single lane bridge can get congested.
Houses on the amenities side routinely sell in excess of 30% more than the other (often much higher if they a period homes in the village centre) even though as the crow flies they are less than a mile apart than those over the bridge. If you compared two similar properties in the village without understanding this it would be easy to think the one on the amenities side was overpriced, when it wasn't.