Here is a quick information I found for Google CSE for business for only $100.00/Year;
Platforms: all Internet-accessible web servers indexed by the Googlebot
Price: free versions
with advertising and limited customization. Note that non-profits, government sites and universities can use this version without advertising on request.
many more options, no advertising, $100 per year for up to 5,000 pages, $500 per year for up to 50,000 pages (limited to 250,000 queries per year) and $15,000 per year for up to one million pages. Other configurations available from Google Sales firstname.lastname@example.org
* Finding Content
o Can include multiple sites (unlimited pages in the non-business version)
o Only those pages within the Google search index are available, no promises about additional indexing.
o No access to pages secured by passwords or other access control.
o Updates to new versions of pages when the Google search index updates (no daily or weekly updating).
o Powerful robot crawler can handle most kinds of links
o Handles file formats: HTML, XML, text, PostScript, RTF, PDF, Lotus, MacWrite, MS Word, Excel, and PowerPoint
o Excellent character set and language recognition for best tokenization
o Does not store the contents of meta tags or page properties.
o Defaults matching all words in the query, case-insensitively
o Uses the Google query language, including Internet Query Operators – (minus) and “” (quotes) , along with OR and various field names and other parameters.
o Optional Safe Search for eight languages (Dutch, English, French, German, Italian, Portuguese (Brazilian), Spanish, Traditional Chinese)
o Light pluralization using an internal wordlist rather than stemming
o Retrieves all matching pages (though the CSE doesn’t say how many that is)
o Shows spellchecker “did you mean?” for misspelled and mistyped words, but they may not have any match on a particular site or set of sites, so it can be a dead end.
o Search results can have “Refinements”, zones based on URLs which appear as links along the top of the results
o Search Suggestions appear using the “subscriptions” mechanism, which is quite poorly documented
o Relevance ranking uses all the Google algorithms, including PageRank
o Adjusting relevance weight can only be done via an XML “background label” and “boost” process
* Results UI
o Default looks like the Google web search results.
o Can display interface in English, French, Spanish, German, Bulgarian, Chinese (Simplified and Traditional), Croatian, Czech, Danish, Dutch, Finnish, Greek, Hungarian, Italian, Japanese, Korean, Norwegian, Polish, Portuguese, Russian, Slovak, Swedish.
o Hides duplicate pages based on snippet similarity
o Page size and cache link seem to appear or not appear randomly
o Basic results page customization: logo, text and link colors
o Option to request XML results and use a scripting language or presentation program to show them.
* Search Analytics and reports
o Shows traffic by hour, day, week, month or “overall” (since installing the search service)
o Shows most popular queries in the same time periods, with links to the queries and flags on no match (zero results) with details.
o Note: report periods for low-traffic search installations may end the previous Saturday, even for daily and weekly reports.
o All admin done via web
o Option to allow “contributors” who can edit the URLs to be included or excluded, and annotate them with any refinement labels that you have created, but not otherwise change the search engine.
Information courtesy of http://www.searchtools.com/tools/google-service.html.