The least expensive patent application

The least expensive patent application is a United States Provisional Patent Application, in short 'US Provisional'. A US Provisional establishes the filing date for the invention described, allows you to mark any prototypes as 'Patent Pending', and commercialize the invention without jeopardizing your patent rights.

However, a US Provisional does NOT mature to a patent, and you MUST follow-up with so called priority patent applications. Priority patent applications are filed in target countries (US, Canada, other target countries) where you want to procure a patent. You can also file a PCT which is an international patent application, as a priority patent application. Priority patent applications must be filed within 1 year to get the benefit of the earlier filing date of the US Provisional.

You can skip the US Provisional, i.e. you can file the regular patent application(s) or PCT right away, and you will get your patent(s) granted earlier, up to a year earlier.