Here's my home-brewed 'PrintMoney()' routine that I use all the time, in the spirit of TMTOWTDI.

my $amount = sprintf ('%.2f',shift());
my $s = length($amount) - 6;
while ($s > 0) {
    substr($amount,$s,0) = ",";
    $s -=3;
}
return $currency_unit.$amount;
[download]

Cheers,
Ben