Scrapping script needed as per my requirement

I have few requirements to fulfill my needs . I would like to collect the sellers data from all type of real-estate websites ,social media marketplaces . So when ever an new listing listed in these types of websites our script should Auto collect the data like name ,number ,pics, discerption, email id etc (What ever possible data available). And these data should be autoloaded into our website or CRM .So from here it has to auto send the sellers and buyers a into message if they are new to us or update message . I would be more happy to explain more if you are got my requirement up to here. So let me know how much or how you charge ? And what are the challenges you see here and how can we overcome?