I have an Alienware desktop. It was, by far, the cheapest solution on the market. I priced everywhere, nobody could do it cheaper than Alienware. I would never have purchased from them otherwise, I was very surprised.
However, post-purchase, I'd have to say for a few reasons I won't do it again. My reasoning:
1. I didn't build it because the parts weren't available. Next time I'll just wait, no reason to be impatient.
2. The Alienware tower is HUGE. I mean MASSIVE. And it's mostly empty. So next time, I'm getting a tower that is either small or actually uses the space.
3. I got a bad video card and my case fan was unplugged. I didn't even realize why I was having heat issues for the longest time until I was cleaning up behind my computer and noticed the fan wasn't spinning. My video card was terrible, artifacts in the BIOS. So much for their QA testing.
In a year or so, when I decide to build a new computer, I will make sure I know what I want, and I will wait till it's available... it's not really worth it to pay the premium to get it now.