Re: Maybe $6k all in to FILE. But additional fees are needed when the patent issues, and to later maintain the patent. Also, often to negotiate with the patent office during the examination process.
Re: Provisional-- But be careful. For example, a Design patent application cannot claim priority to a provisional patent application. So the article's advice regarding filing a provisional patent application would not apply to design patent applications.
Re: Provisional-- But be careful. For example, a Design patent application cannot claim priority to a provisional patent application. So the article's advice regarding filing a provisional patent application would not apply to design patent applications.