my @bes = (1111, 2222, 3333);
my %waren = (
    "plastik" => {nr => 1111,preis => 1000,verf => 'J',},
    "metall" => {nr => 2222,preis => 2000,verf => 'N',},
    "holz" => {nr => 3333,preis => 3000,verf => 'J',},
);
for my $k (keys %waren) {
  my $nr = $waren{$k}{nr};
  $waren{$nr} = $waren{$k};
}
print "Bestellnummer: ".$bes[1]."\n";

print "Preis: ".$waren{metall}{preis}."\n";
print "Preis: ".$waren{$bes[1]}{preis}."\n";