Is it some kind of a Meta search engine or it uses its own search algorithm to present search result ?
Info is on the site and the main OP.
OP says volume about the money flow, but not much about how the search work. How about giving a direct answer or at least quoting the relevant portion ?
There is no default search engine to searchtrade.com any developer can build a search engine and make it part of searchtrade. The reason is we believe there must be more choices for users. You can use Google, Bing, duckduckgo and other major search engines at searchtrade as well. They are all listed in a search app market.
That pretty much explains it. So, you are more like adwords, where keywords get sold. Now, adwords get used on Google and other website, whereas yours can be extended to any search engine allowing API.
But, why would advertisers advertise in a system, where they know that people search for money, not to find what they are searching for ?