my $value = '$100';

if( index($value, '$') > -1) {
  print 'found "$" in $value';
} else {
  print 'no "$" in $value';
}

__output__

found "$" in $value

##</code><code>##

my $value = '$100';

if( index($value, '$') == 0) {
  print 'found "$" at beginning of $value';
} else {
  print 'no "$" in $value';
}

__output___

found "$" at beginning of $value