Get product price from amazon website, ruby, mechanize

amazon_get_price.rb

#!/usr/bin/ruby

require 'rubygems'
require 'mechanize'

# to avoid 'ran out of buffer space on element' error
module WWW
  require 'hpricot'
  class Mechanize
    Hpricot.buffer_size = 262144  # added by naofumi
  end
end

$agent = "Linux Mozilla"
$site = "http://amazon.co.uk"

def get_price(url)
        agent = WWW::Mechanize.new
        agent.user_agent_alias = $agent
        page = agent.get($site + "/" + url)
        title = ''
        # uncomment if you want product title as well
        # title = '#' + page.search("//[@id='productTitle']").inner_html.strip
        return  page.search("//[@id='priceblock_saleprice']").inner_html[1,10] + " #{title}"
end

unless ARGV[0]
        puts "Need one arg: product_name/dp/ASIN_number  (copied from amazon product url)"
        puts "example: amazon_get_price.rb Massage-Stress-Reflexology-Porcupine-Sensory/dp/B00M776F12"
        exit 0
end
puts get_price(ARGV[0])