Charger Port not working.

i've had my macbook roughly three years? about i think and just last week my my charger cord decided to short out, unplugged it from my mac before it went up in spasrks. so i went out and bought a new cord, plugged it in no green/orange light. cleaned my port out, plugged it in, bam it works. i pretty much keep my mac plugged in at all times so then i unplugged and went to work yesterday and tried to plug it back in and once again it wouldn't charge. tired cleaning it out, worked last time why not this time. still nothing. pretty positive its the port.

was just wondering how much its going to cost me to get it fixed? please say under a hundred dollars!