Can I make a contract with somebody to improve my property in exchange for a share in the property?

I would like to formulate a contract whereby my property price is fixed at the minimum amount possible and the person's labor is fixed at the maximum amount possible in order that he work in exchange for a share in my property. I am thinking that about 12-18 months is the length of time I want it to take him to acquire a 50% share in my property, after which the contract would terminate and any further work performed would have to be under a new contract. (I have worked with Robert Murillo before, but I guess this form is not specific to Mr. Murillo.)