I'd pass on that -- if for no other reason then because laptops don't really make for great gaming. The more demanding the game the more its going to tax your processor and battery. Having a potentionally wireless connection won't do to well for things like MMOs, either. So by time you address those two problems (keep it plugged in and have a wired connection) you might as well be running a Desktop.
I'd second saving a bit more and building a Budget Desktop. Dollar for dollar, you'll be getting the best bang for your buck with a Desktop. It'll also be easier to upgrade your rig as time and money comes. It's a bit harder to upgrade a laptop and even you'll likely reach a point where it won't be worth it.
Also like three Red Flags waived about the seller simply reading your description.