You can start with a book proposal. Most commercial publishers of non-fiction would rather see a proposal than a finished book. When they decide to sign you, they give you an advance on royalties, which should cover part, if not all, of what you'd pay your ghostwriter. This reduces your risks as well as your up-front costs.
A proposal consists of a brief synopsis, a detailed outline, an author bio, a market overview and marketing plan, and a sample chapter. It usually runs about 15,000 words, and takes know-how. Even if you intend to write your own book, you might prefer to have your proposal written professionally.