phone_searcher.rb

#!/usr/bin/env ruby

# Do this:
# gem install httparty nokogiri

# Then run this file...

require 'httparty'
require 'nokogiri'

class HtmlParserIncluded < HTTParty::Parser
  SupportedFormats.merge!('text/html' => :html)

  def html
    Nokogiri::HTML(body)
  end
end

class Page
  include HTTParty
  parser HtmlParserIncluded
end

url = 'https://play.google.com/store/devices/details?id=nexus_4_16gb'

loop do
  res = Page.get(url)
  res.css('span.hardware-sold-out').each {|l|
    if l.content != "Sold out"
      puts url
      `say "Nexus 4 is on sale"`
    end
  }
  sleep 30
end