I've been looking for something very similar. For that price range though, you won't find much
You can look at this it has a lot of great deals:http://www.gaminglaptopsjunky.com/gaming-laptops-under-600/
If you're willing to go a bit higher i would recommend the Lenovo Y580
You should buy it soon though, there are a lot of amazing deals going around because of Cyber Monday and Black Friday and the like.
Check out that website: gaminglaptopsjunky.com it's really useful.
Use this to check out the Graphic cards and their compatibility with games: http://www.notebookcheck.net/Computer-Games-on-Laptop-Graphic-Cards.13849.0.html
Also stay away from ULV processors (pretty much any processor with U in the name) they're underpowered and not the best for gaming. But if you're looking for desktop replacement you won't find those anyway.
Don't hesitate to ask more questions