engine
You must make sure that the web sites that have the ready made searches you are taking advantage from have their own search engine. Meta searches will not do it as you will get to broad results. Also make sure that the sites you use have been around for a while. New sites tend to have less opportunities than older sites. The older sites has build up a cache full of search results so they can serve you very quick, they also know what people want. If you have to use a new site, expect to wait a bit longer for the search results. Another thing to remember is that it is best to use sites that are dedicating them self to one country. Then the search results will be very specific to what you are after. An example of an old site that is restricted to only one country is norge online. This site crawls the whole norwegian web for you and deliver results quickly on demand.