The ED station isn't too bad because AFAIK all the trains that pass by stop there, so if you're next to the station they will be either accelerating or decelerating, ie slow either way. Plus being close to the new Charter secondary will be a plus for many.
I have seen properties next to stations on the Clapham Junction to Croydon line, and those tend to be cheaper because they're much noisier from all the fast trains speeding by without stopping.
However, this new build is literally next to the station, so there is a chance of hearing all the announcements.
Oh, well, it's a free world, if others want to pay close to half a million for a one-bed there, it's their right!
Also, asking price doesn't necessarily mean sale price!