Use the regex engine just to locate the number. To see if the number is between a thousand and a hundred thousand, use the built-in Perl implementation of arithmetic.

while (<>) {
    chomp;
    print "$_: ";        
    if (my ($number) = /^\$?(\d[,\d]*)/) {
        $number =~ s/,//g;
        print $number < 1000    ? 'too small' :
              $number > 100_000 ? 'too big'   :
                                  'just right';
    }
    else {print 'not a number'}
    print "!\n";
}
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