I chipped my tooth by my gumline. How severe is it? What is best the treatment for it and how much is it typically? (Photo)

It appears that part of the tartar build up on your tooth chipped of and not the tooth itself. You would need to visit a dentist for evaluating the condition of your gum and bone and prescribing the right type of hygiene treatment.  

It appears you have not visited a dentist for a cleaning in quite some time, and calculus (tartar) has significantly built up on your teeth. Some of that has broken off, and that is what you are feeling with your tongue.  You should visit a dentist for a complete examination and begin your dental cleaning procedure which may involve more extensive cleaning techniques. If you do not get this calculus cleaned off, it will cause the bone that holds your teeth in to dissolve away. This may have already occurred to some extent and should be evaluated immediately so you do not lose teeth to gum disease.

From your photograph, it appears you haven’t chipped your tooth, but the calculus (tartar) that had been growing there. This is plaque which has been allowed to sit on your teeth and harden with time. I would suggest you get yourself an appointment with a dental hygienist to have that removed and your teeth and gums checked. Also, your dental hygienist can show you how to prevent that from continuing to grow, which is important because it contains an astounding amount of bacteria!Good luck!