By far, the best and most inexpensive OS X experience on a netbook can be found on a hacked Dell Mini 9. And now you can get your hands on one for only $200.
Needless to say, if you want to run OS X but can't afford a pricey Mac, this is definitely the way to go. And all you need to do is follow these instructions to get your OS up and running. Better hurry though, this could be your last chance. [Dell]