I can help you with this pretty well, I just finished building my new rig a few months ago. That means I can tell you what will work and what won't. Are you looking for a desktop or a laptop?
If you're after a desktop, it'll be much less expensive than 4,000-5,000. Though the price will ultimately depend on how high you want your settings to be. I usually don't find much difference between the highest settings and the recommended settings. Your opinion may differ.
If you're after a serious gaming laptop, you might be looking at something more in the 4,000-5,000 price range. Those things are really expensive. If, however, you want a laptop that simply can play games then you are looking more likely at 600-1200 dollars. I got my laptop for 800 at Best Buy. It runs Starcraft 2 on recommended, Guild Wars 2 somewhere between recommended and minimum (still looks great anyway), and all my other games at whatever setting I want.
Once you give me a bit better of an idea what you're looking for I can give you some suggestions.