The thing about pawn shops is sometimes musicians have money and sometimes they don’t. They pawn instruments with the notion of times improving and having the money to get the guitars out of hock. Sometimes they can and sometimes they can’t. You are more likely to find better quality guitars at pawn shops than Salvation Army as Fly said above.
Some guitar shops (e.g., Sam Ash) will sell used guitars on consignment, but the prices aren’t as good as pawn shops. Also pawn shops have mixing boards, speakers, and all kinds of other things that musicians temporarily do without while raising the dough to get them back.