Many netbooks are around $299 US. They have small screens and they are not very fast. But for a lot of tasks that is not a problem. I think they are wonderful for writing, and they work great for most web surfing and playing music. And you can plug in a bigger monitor when you are at home.
Laptops start at around $400 US. As the price goes up, you pay for a bigger screen, a smaller lighter machine, a faster machine, maybe longer battery life. No machine has all of those things, so you have to choose what is important to you.
For me, $500 to $700 is the right price. The more expensive machines do not seem much better to me. And the cheaper ones are usually lacking some feature I want.