They are expensive yes, but you need to think about it. Look at the monitor you are getting, a fantastic LED & IPS glossy screen, by far the best monitors you can buy, which include hardware built in to it. Yes its mobile, but what do you expect? Apple don't feel they need a separate box like PC, apple is elegance, simplicity and functionality. No your not gonna be playing Crysis 2 on very high settings on this thing, but these are not really made for gaming for the most part, they are made to be give the best browsing experience, the best productive experience and the best media entertainment experience.
If you want hexacores and 580s in SLI, go build your own and enjoy wrestling with it to beable to get it to work right, and even when it is working right expect it to play up often.
Imacs, macbooks, mac minis, they are all machines that grant peace of mind, yes they have problems but they are far and away less problematic then pcs. Why? Apple controls everything, they build the hardware and the software and so you can be sure you have garenteed compatibility. Yes they are expensive, but as I said, you really do get what you pay for it. An extremely high quality and pleasant experience.
So chillax dude.