Best/Cheapest way to buy a Mac book? Should I buy the new Mac book Air, or wait for 2013 Macbook Air?

I've wanted a Macbook air for quite some time, i have a Samsung qx411 laptop which i got for cheap, but i commute a lot from home-to-school-to-work, so something 2.5 pounds lighter will be helpful. So i was wondering if i should wait for 2013 or should just buy the currently new Macbook Air? And if i should just buy the currently Macbook Air, what is is the best cheapest way to buy one?