Google Commerce Search

Google Commerce search will take your product feed and presumably index it for quick site search.
With Google Commerce, they will replace your site search with their own … what? It appears to be a site within a site. 
Pricing is based on how many products you have and how many searches are done. Just think every time the customer uses your Google Search on your site, cha-ching, google makes money!
So if your search engine and product filtering tools are not good enough don’t waste money investing in fixing that, pay Google to do it for you. 
Read more about how to pay for people to search on your site here