Unless you have scripts disabled on your browser then many websites will track you all over the net. That's why you'll end up seeing numerous ads which look strikingly similar. Should you click on any of them ads then you'll be seeing more and more of them in future in case you are logged into your email accounts [if you use Google that is] because your searches are saved and you'll get the same search results most of the time when you use the same keywords to find something. To avoid seeing the sites whose ads you've been seeing in your search results when hunting for great deals, clear your browser history, clear cookies, etc and log out of your Google accounts. This will aid in your search for great deals because the search engine won't favor any sites [based on your browsing habits].