If you're not going to keep it, that's even more reason to buy a used MacBook as MacDoc suggested. You can use it for the time needed, then resell it on Kijiji for probably the same money as you paid for it.
Netbooks just plain suck, please try one out before you commit yourself to buying one. The keyboards are bad, trackpads are terrible, screens are poor quality, battery life is bad (you can buy extended cells, but what's the point then), they're not even that small. Most, if not all, are over an inch thick.
Those old white Macbooks that MacDoc mentioned are a good idea, I just sold a mint '2011 one for $400 back in the winter.
Netbooks aren't amazing but I AM getting 10 hours or so or so of batter ylife with mixed use. And I DO get weeks of standby and pretty closeto instand on. And I don't think mine is an inch thick.
.Tom