I think what you`re talking about is a "contingent fee" arrangement. They get paid if they succeed in meeting your milestone.
While such agreements are possible, your question is missing a lot of important information. Most important is what is the scope of work? What do you want the consultant to accomplish? How can the consultant be certain they will be paid if they succeed in meeting your milestone?
You can hire anyone you want on a consulting basis. For the most part it doesn`t require a license unless the work they are doing requires a license under state law.
I`ve done consulting and my biggest concerns if I had a proposal like yours would be the definition of this milestone, and if I met it, would you be able to make payment. It`s difficult to imagine a consulting expending a lot of time and energy on something unless they have strong assurances of payment.
In my current business, my fees are contingent in most cases. I don`t get paid unless I successfully get financing for a business, and that`s why I`m careful about qualifying a business and a business owner before I take them on as a client. You`d need to convince me you`re worth the effort although fortunately I woudn`t have to rely on your promise for payment because I`m paid by the company doing the funding.
Regional Vice President
Equity Corporate Finance, Inc.
888-498-8999 ext. 109