Reading the OP the question is... why do people go silent and not commit to buying?
Well, I for one would never get a quote from one person and not shop around (I would hope most of us are the same).
Maybe people have received a price, shopped around and decided to go elsewhere.
some comparisons have been made to dealers, plummers and insurance companies, which i'm not sure is relevant to this thread as all are companies and not "a guy on a driveway" cashing in AND NOT declaring additional earnings to MR HMRC. ka-ching!!!
If your running the retrofitting as a business like Ed, you can expect to be charged a premium. However, I don't find Ed charges ridiculous sums for his installs AND you know he knows his shizzle. lol
I'm actually now wondering who the extortionists are on the forum.
End of the day I don't think people should give a price for an install and automatically expect to get the job.
My 2 pennies