Munging the data 

use 5.020;
use strict;
use warnings;
use autodie;

my $product_file = 'product-list.txt';
open my $fh, '<', $product_file;
while ( <$fh> ) {
    s/GBP/£/;
    s/EUR/€/;
    s/USD/\$/;
    print;
}