How to Make website like NexTag ?

Hi there,
I have question
I see nextag website show price comparison about product mostly at Amazon,
I want to ask
How can I make website like nextag, the website that automatically pull all data (price, description, picture) from all store and put it on website
For example I want to sell ?[FONT=&quot]makita cordless drill[/FONT]? , so I want to give people price & shipping rate, likes nextag given to buyer


really appreciate if someone could guide me

there are a couple peices of software that do stuff similar to this. If you want to actually source from shopping.com/nexttag etc, they all will provide you with feeds of data that you just plugin what your loocking for. here is the best one out there


http://www.datafeedscripts.net/


but its pricy