First, welcome to the club. It's an addicting one. My first advice is do some searches, both here and at RFC. It's ALL been asked and answered over and over again. Having built a bunch of these up, I can say the big names aren't always the best choice by any means. You'll very likely do better to build it pice by piece rather than buying a pre-built one.
You say you want "high-end". Is it for simply having the name and whatever prestige supposedly comes with the name or is it indeed for the top level performance? If the later, yeah, build it yourself. If the former, don't waste your money. Having the big fancy stuff is moot if you don't use it for it's intention IMO.
So, yeah...do the searches, read, search some more, it's all there.
Feel free to shoot a PM this way if need be.