Issue regrading book search for finding a lowest price of the book throughout internet

So first, you have to start look for the most interesant rss feed according to the book in the markets then you can interogate them though a WebClient object

WebClient client = new WebClient();
client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(
      client_DownloadStringCompleted);
client.DownloadStringAsync(new Uri(
    "http://feeds......"));//your feed path here


void client_DownloadStringCompleted(object sender,
  DownloadStringCompletedEventArgs e)
{
 
  //Get the information in an xmlDocument
    XmlDocument document = XmDocument.Parse(e.Result);
 // and the you can deal with information either by applying xsl or by querying data
 //using LINQ
}

One remark: You shouldn't test it from your local site you have to deploy it in the internet or at least create a virtual repertory with IIS an deploy your application there then test it