For that repair to be done properly it would need to be done in a bodyshop as the paint would need to be blended through the door. You would probably be looking at approximately £500.
If this was done by smart repair means i.e. chips away, the painter would take it edge to edge and you would notice the difference in the shade of paint against the door. The paint finish would never be the same quality as a bodyshop as an infra red lamp and small nozzle guns can't compete against an oven baked on paint in a spray booth. Then there is the added problem of contamination in the paint. Smart repairers paint outside, not in a sterile oven where the dust is extracted.
Don't get me wrong. Smart repairers are fantastic for bumper corners where the repair is down below etc. But one thing to bear in mind is what the repair will look like in six months time, especially when painted in alabaster. This is why smart repairs are great for the trade. Once the repair is done and the car is sold, the car is never seen again.
The other option would be get the dent removed by Paintless Dent Removal (don't call dent master, as there is no such thing anymore), then touch the chips in yourself.
The repair will not be invisible, as you would still be able to see the touch ups, but it wont be an eyesore and you have the added bonus of keeping the paint original on the rear quarter and it won't impact your pocket as much as the bodyshop route.
One thing to bear in mind is the individual skill of the PDR tech. It is more of an art than an exact science. Generally the techs that work at the main dealers like the Honda one you went to see are at the higher end of the skill level and haven't just bought a bunch of bent rods off eBay and done a one week course in dent removal.
Here is a small example of what can be done with paintless dent removal. All of the repairs where done by myself:
YouTube - Paintless Dent Removal Repair examples