Extension of Numeric with generic data retrieval. Currently limited to pricing from Amazon.

numeric.rb

require 'httparty'
require 'nokogiri'

class PlauralObject
	def initialize(name, number)
		@name = name
		@number = number
	end

	def cost
		resp = HTTParty.get "http://www.amazon.com/s/?keywords=#{@name}"
		html = Nokogiri::HTML.parse resp.body
		prices = html.css('.newp span.bld.red').map { |e| e.content.strip.gsub(/[^\d\.]/, '').to_f }
		average = prices.reduce(:+).to_f / prices.count
		average * @number
	end

	def price
		cost
	end
end

class Numeric
	def method_missing(name, *args, &block)
		PlauralObject.new name, self
	end
end