Equivalent 27" 1440p Dell monitor is about £600, £1000 ish for the computer, plus it looks beautiful as a piece of furniture in my living room. Definitely good value for money imo.
Rub, an iMac doesn't have £1000 worth of components in it, nowhere near it. I put together a build using Swedish prices, and I only got to about £700. I also found a 27" Dell IPS for £200 less than the £600 one, with no difference between the panels. Sum: about £1100, with a 120GB SSD + 1TB HDD. In comparison, a 27" iMac costs about £1700
without the fusion drive. Not only is my build cheaper, but the components are higher quality and easier to upgrade; several free PCI-e slots, multiple hard drive bays, power supply with lots of connectors, everything removable/installabe using only a Philips screwdriver and you don't have to use tape to reseal the case.