while (my $line = <INFILE>) {
   my ($date, $description, $amount) = split /\t/, $line;
   if (defined $amount) {
      print OUTFILE $amount;
   }
   else {
      # Amount not found...
   }
}

##</code><code>##

while (my $line = <INFILE>) {
   if ($line =~ /(-?\$\d*\.\d*)/) {
      print OUTFILE $1, "\n";
   }
   else {
      # Amount not found...
   }
}