Look on Amazon or possibly even eBay for a used gaming laptop and you can get a damn good machine for pretty cheap if you can snap a used one in good condition. That's what all 3 of my gaming laptops have been: Asus G73jh (refurbished from Newegg... $760), MSI GT780DX (used from a forum...$760), and my current GT70 2oc-059us (used off of eBay, $1100 - sold my GT780DX so the upgrade was only about $400 for the new laptop).
Brands to look for would be MSI, Asus, and Sager (a rebranded MSI essentially). They're going to have some of the best cooling which is EXTREMELY important for a gaming laptop of ANY kind. Gaming laptops can run hot, and having a good cooling system to get rid of that heat is important.
Specifically what games are you wanting to play?
Do you want a 17" screen or is a 15" screen fine?