If patent costs are still beyond your budget, you have other choices. The U.S. Patent and Trademark Office (PTO) offers inventors two other ways to file and document the date of invention. Although these filings don't replace patents, they offer some legal protection. The second option is:
Provisional patent application: Recent changes in nondesign patent laws (following the United States' 1994 passage of the General Agreement on Tariffs and Trade treaty) now allow for the filing of a provisional patent application. This includes a description of the invention; drawings may be required if the description is not clear. It doesn't, however, include an oath or declaration, patent claims, or the specified drafted drawings that are required with a full patent application. This application proves you've filed a patent application and allows you to claim an early priority date.
Filing a provisional patent application places your invention in "patent pending" status and gives you an additional year to follow up with a formal application. If you don't file a formal patent application, however, you won't receive protection. Unlike the disclosure document, your application will be reviewed for compliance by the application board. The fee for filing a provisional application is $75. This option is helpful if you're running out of time to file your patent and need to establish a filing date.
Filing a patent with the help of a qualified patent attorney is definitely the best choice if you truly want to protect your idea. Although it's expensive and time-consuming, filing a patent is the only legal means available to you to defend your invention. For more information on patent applications, the PTO has a very informative Web site designed to answer patent applicants' questions.