what you end up using as rollers under it should be determined by cost, and ease of procurement. also by hardness of the ground where you are...know anybody with a bunch of old metal fence posts sitting around? (I just gave a couple dozen away). or maybe someone with old (large diameter) water pipe? you could just borrom 'em, and pull the thing with a rope to your car bumper...perhaps.
in my experience, trying to lift a shed with a 2 x 4 as a lever may be futile-the thing'll snap before it starts to lift. try a small scissor jack (I keep 3 old datsun scissor jacks aroumd for just such things). got some great crowbars, too: 1.5 inch in diameter, six feet long...where do you live? a piece of 2 inch water pipe would make a FAR better lever for lifting than a 2x4...wooden wedges are always helpful....
good luck