Depends where you go. Not very much 15-30. I got my left ear done at claires because it was cheap(15 for one). Did my right myself and gauged it to 6 right away.
It doesn't hurt very much. just a little prick. With a gun it will only hurt for a couple seconds. Not sure with a needle. It didn't hurt much for me when I did it myself.
Probably the piercings that hurt the most are cartiledge(Can take up to a year to heal). Least are lobes and penis actually. Genital piercings don't get infected very often either.