I need to extract data from a website, say for eg. Buy.com's Electronics category
and save it either in MS excel.
I tried looking for the code over the internet, but this wasn't properly explained anywhere.
Please help me.
Look up the php manual and search file_get_contents() - your host may have disabled cross-domain use of this. If so use cURL. There are a few other methods too, but I think those two are the most common.