That's more of a startup oriented attitude. To continue the house analogy, if you wanted to avoid the premium associated with the higher contract, could enter into a similar agreement with the builder.

He builds the house on the cheap, in exchange for a percentage of the final selling price. If the contract was sound, why wouldn't that be an equitable deal?

There's probably a law against it, though (houses are funny that way).

In the case of the original post, I would be willing to work there - as a very expensive contractor, with the degree of my loyalty explicit in the terms. He'd probably object to the part about him paying my attorney to review it, though.