No it was me who asked for a combi boiler quote but was surprised at the mark up from what a boiler would cost if I supplied it from Screwfix with the added £2100 for one admittedly one long days work for two which made me think like for like now
There is more work than you think in that job. It isn't just a mark up on a boiler.
There will generally be:-
Flush system
Remove boiler, cylinder and tanks.
Install new boiler.
Alterations to pipe work.
Additional controls & Wiring
Alterations to gas pipe work
Installation of condensate drain
Fill, commission and balance system, dose inhibitor.
Brick flue / repair existing hole etc.
Tube, fittings, boiler, flue, controls, filter, disposal of waste and scrap etc.
Provide a 10 year warranty,
This will hopefully be carried out by competent, skilled, qualified and fully insured tradesmen.
A lot of folk look at what they can buy the boiler for and think the same. Before you do go down that road, make sure you can find a tradesman to install materials provided by you. I wouldn't do it and the vast majority of tradesmen I know wouldn't do it either.
If you're thinking of a regular or system boiler and your system is old enough to have gravity hot water, you may need to change more than just the boiler. The new boiler, whatever type, will need to be fully pumped.