Google is to make its custom search engine available for small businesses without ads.

The tool, which allows webmasters to limit queries to a certain set of documents, on one or more websites, will cost between $100 and $500 a year, depending on the size of the business.

If differs from the free, ad-supported custom search engine as Google offers technical support for its users.

Businesses could, for example, place a ‘buy it now’ button next to search results on a website that links to products.