Gas fuel gauge needle doesnt work

Ok well ya my Gas gauge (the empty/full guage) doesnt work correctly

I fill up my tank,and sometimes itll read full, sometimes be in the middle

when im empty itll read full, or in the middle and all that

basically it moves to random spots, so i cant really tell how much gas i have (i just refill every 270 miles)

So ya how can i fix it? what exactly is wrong with it?

My dad said it would cost about 200 bucks to fix

Sounds to me like a bad fuel sending unit. They are costly units to begin with and you have to drain the gas and drop the tank, and if your familiar with doing that at all its a real pain in the a$$, and if you bring it somewhere it gets really costly. Not sure what to tell you, since if my fuel guage didnt work, that would be one thing I wouldnt be able to live without. Check all the circuitry, look for bad grounds. It could just be something that simple.