Patent lawyers often take cases on a contingency basis, which means you don't have to pay up front. The company that is going to manufacture your invention may be interested in such a deal. Some inventions, like recipes, may be better off kept as trade secrets. That's what the Coca Cola Company has done for years with its soft drink formula, which remains a cherished trade secret that has never been patented. The choice of whether or not to patent an invention or keep it as a trade secret is often dictated by commercial issues.
Trade secrets do have legal protection against disclosure.
And if an employee leaves to work elsewhere, the manufacturer can ask that the new employer not encourage disclosure of the secret process. It's also possible to file suit in court to prevent disclosure. The first step is to prepare an application, which is then filed with the Patent Office. Your application should give a very detailed description about how best to make and use the invention. Sometimes, if a patent application is well-written and describes a functional and reproducible invention, the application itself may be sufficient.