My family has pretty much come to the idea that laptops are basically disposable. We go for cheap. Just make sure there is enough RAM and a big enough hard drive to handle whatever it is you plan to do with it. None of us are big "gamers" though, or doing anything that requires a huge amount of computing capability.
We tend to look at the various retailers and see what's on special that week/month. We have been able to outfit our whole family with laptops, by buying the equivalent of "last years model", in the $300-$400 range.
High schoolers are notoriously hard on laptops, too, which is another reason to not spend too much money on it. The likelihood that it is going to be dropped, stepped on, spilled on, left in a hot car, lost or stolen is much higher with a teenager. My opinion is go cheap and don't sweat it too much.
My two cents.
Meg