I have a 6ftx8ft coop (a converted kids playhouse ) made from very sturdy 2x4's and 2x8's. It's heavy to say the least. I moved it by myself with a 2 inch pipe, a car jack, a few 12x12 concrete pavers and 2 old bed casters. I dug under the front and used the floor jack to lift the front end. I got it high enough to drill holes for the bed casters and set it down gently onto the concrete pavers. Then I jacked the back side up and put my pipe down. After that it was just some good old shoving power and moving my paving stones to keep the casters on solid ground. Worked out great!

This photo was taken before I moved it but you can see it's quite sturdy and heavy.
It was originally too close to my back fence and I moved it a few feet but there's no reason why it wouldn't work for you. I would suggest a larger pipe though. I used a 2 inch because that's what I had laying around and I didn't want to buy one.
Here's a great video of a group of kids moving a large shed on youtube.
How to Move a Shed
I was pretty inspired by this video and figured if a bunch of kids could do it, so could I.
Let us know how it goes!

This photo was taken before I moved it but you can see it's quite sturdy and heavy.
It was originally too close to my back fence and I moved it a few feet but there's no reason why it wouldn't work for you. I would suggest a larger pipe though. I used a 2 inch because that's what I had laying around and I didn't want to buy one.

Here's a great video of a group of kids moving a large shed on youtube.
How to Move a Shed
I was pretty inspired by this video and figured if a bunch of kids could do it, so could I.

Let us know how it goes!