Lesson in economics for all the numpty's moaning about what heating engineers & plumbers earn:
Don't mistake a heating engineer's TURNOVER figure for his or her's PROFIT for a job. If the job costs you £3k and the installer is forking out £1500 for boiler & radiators, then he's not making £3k on the job is he ?
Besides, its a market economy people, so what if someone is an architect / plastic surgeon / airline pilot or whatever - could any one of these people live without hot water, or get through the winter without their central heating??? I can live without getting my house extended!
I did 4 years at University, but that didn't give me the belief that I should be paid better than someone else. I then had to graft my bloomin ballcocks off to make a good go at this heating game when I changed career, now I'm paying all of the aforementioned bills (tax, insurance, time off work etc) and trying to get by.
Regarding your quoted prices, to decide whether or not they are reasonable, take the quoted price, deduct all expenses no matter how small (boiler, rads, amount of pipework & cable, pipe clips etc), estimate the installers weekly expenditure including all the costs that people forget that we have to fork out for (phone calls, fuel, insurances, wages paid, etc etc), then you will have arrived at:
the PROFIT the installer has made!!
Usually less than you think...