I mean by public a person, a civilan acting on his or her private time, a user of the web. I am really not aware if I can enter the building being an homeless in San Jose, Ca, USA. I follow the Law at all time; but I am not a member of any group or any companies.
A few hundred dollars at first, around 5-8 thousand if you want a patent attorney.
Later the maintenance fees go up, but you can always abandon the patent / application.