A MacBook Air could be worth a look, depending on what you’re doing with it. The hard drives aren’t massive in the Airs, but you’ll get better battery life, and they have SSDs in them which means they’ll be pretty rapid. However, you can’t upgrade a MacBook Air aftermarket so how you buy it is how it stays.
If, as the others have said though, you only want it for general use (web browsing, emails, iTunes, etc) then you really don’t a CPU as big as in that model, and you’ll probably find the computer feels more responsive if you were to go for something with a smaller CPU, but an SSD instead.