If you manage to get $99 extra on your budget you'll be able to get a Mid-High end (performance) and Mid end (graphics) laptop at xoticpc (MSI CX61 2PC-499), look for reviews about the site.
Only thing I have to say about this is that MSI has been a gamble with problems. You might get lucky and end up with a good reliable computer, or you might get a lemon of a computer. I prefer ASUS and ( Toshiba and HP Business Class Laptops ) for higher quality than their normal consumer product lines.
$600 is pretty tight for a new gaming laptop so you may end up having to get a used one.
Used comes with risks, but if your trying to stretch your dollar, you could get a ok gaming laptop used for about 50 to 75% retail cost.
I use to buy used desktop gaming systems on the cheap such as a Pentium D 3.0Ghz with Fatal1ty motherboard with SLI and a pair of PCI-E GeForce 7800GT's in it with 1.5GB DDR2-667Mhz RAM and a 80GB HDD for only $80.00 with Windows XP on it and this was back in 2007 when that was a sweet system. I ended up running this system for about 2 years and then selling it for $75 to a friend who needed a gaming system. I needed one of the video cards and so I undid the SLI config and had it with a single video card, so for $5 I ended up getting almost 2 years of heavy gaming out of it and a video card to place into my newer build for $5.
When it comes to laptops though there is a high risk that you might be buying someone elses problem though. I have seen many used laptops that the GPU's have been cooked on them and they will boot up and act fine until you run a game on them in which soon you start to see pixelation or colored lines appear from out of nowhere.
If buying a used gaming laptop, I'd suggest buying it through a person you know that isnt going to sell you junk or a computer shop that has a name/reputation to maintain in which you being happy matters.
Places like ebay and craigs list you have to be really careful with not buying junk.
Lastly my biggest issue with buying used laptops was being concerned that the laptops could be stolen property that someone is trying to pass off. Some people might claim they dont care if the property is stolen or not as for they didnt steal it and so no harm done, but buying stolen property feeds the problem, as well as you could get sucked into a legal battle with receipt or posession of stolen property. So used systems that I have bought through the years, """especially laptops""" I generally deal with friends and friends of friends who can be trusted not to be selling junk or stolen property.
