uPVC with foundations and a knee wall circa £18K. I did have one quote that hit £25k though. A lot will depend on which part of the country you are in and what extras you want, manual or automatic vents, fancy bi-fold doors or sliding etc.
Depends on the area you live, what the ground is like, what is it attaching to and what speck u want. If on flat ground, and a standard upvc installation with a dwarf wall, then I do them for around 7k fully fitted plastered and guaranteed.
Mojo, I have no idea what part of the country you are in but we have looked at a whole range of conservatories and fitters and DIY options and we could never have got it down to your price. Either I'm getting Southern Jessie prices or you are selling yourself cheap ;-)
no one has mentioned one important point which is to make sure that you have suitable foundations for your location and soil type. I have a friend who is tearing her hair over this at present.
Definitely not selling my self cheap, competition is high in Yorkshire and we do one a week, mostly on recommendation. But I do know there still expensive in the south