Hi, like anything else, you get what you pay for generally........however, a lot of kitchens out there are very overpriced ( Moben spring to mind...) I spent 10 years specialising in installing kitchens and have fitted them all from the cheapest B&Q crap to Bulthaup and £70,000 bespoke jobbies.......The one thing I can tell you is that how its installed will make a huge difference. If you are not doing it yourself ( and don't underestimate what's involved, so many times I have had to refit kitchens installed by builders or chippies who thought they could do it. You need many specialised tools and jigs to do it properly) employ a specialised installer. A recipe for a successful fit is proper planning of all the services and connections. Many times we have installed Ikea units with a nice granite worktop and they look a million dollars. But you have to get around the weird design ........However, while very cheap, i find the chipboard is not as dense as Magnet or Wickes units. You also have to think about the useage. If it's just you and the wife and you are going to look after it well, an Ikea will serve you well, dressed up with decent drawer runners, hinges, fittings etc. Beware of cheap worktops, really crap. If you are using formica, use Duropal or similar quality product. I fitted magnet kitchens for many years and always thought they were very good. Only thing I disliked was the flimsy hardboard backs to the units, but I think they have changed these now. Wickes are also good and Howdens not bad either. I also spent 3 years doing contract installs using crown products and they were always well made.
HTH, Mark