and then you will see just how much cheaper real trade prices are compared to what most installers pretend they are paying. ..
Could you clarify what you mean by 'pretend they are paying'?
An independent, private installer, in the one-off trade, pays no less for a boiler than a member of the public.
The prices you're talking about aren't 'real' trade prices at all, but those that are supplied by the manufacturer with special contract support. Otherwise no-one can afford to supply them.
Indeed the only way manufacturers can afford it is by increasing prices for the independent installers, landlords accuse of ripping them off.
We are subsidising the cheap prices you now get to undercut us with,
which is sort of the whole point of the angst in this thread.