#!/usr/bin/perl -w
use strict;

my @bucks = ('$1,999,003 USD ', '$1,532.33 AUS', '$1,500.11 USD');

foreach my $amount (@bucks)
{
   next unless $amount =~ m/USD/;
   my ($comma_amount) = ($amount =~ /\s*\$([\d,.]+)/);
   print "c=$comma_amount\n";
   (my $number = $comma_amount) =~ s/,//g;
   print "n=$number\n";  
}
__END__
prints:
c=1,999,003
n=1999003
c=1,500.11
n=1500.11