I don't think it is nearly as heavy as you imagine. The framing is steel, but the walls are welded wire. I have a coop that is steel framed with aviary mesh sides (like chicken wire, but with teeny, tiny openings) I don't move mine around much, but could (and have) if needed. Oh, and it has a skylight roof, which adds a LOT of weight.
I do agree that it is pretty expensive at $750, but metal is pretty expensive. It looks very secure.