How can I clean my SD card slot?

I almost had a heart attack this morning when I was trying to upload 200 photographed documents from my camera’s SD card. My computer wasn’t reading the card, although my camera still could.

I figured out it was because the SD card slot on my mac is dusty as all hell. I haven’t used it until this summer.

Keeping in mind that I am a broke traveling student eating two meals a day, can anyone please suggest a good way to get some of the dust out of there?