Research for Nothing and Law for Free?

Jerry Lawson compares Free Search Engines vs. Westlaw & Lexis, which prompts Tom Mighell to ask: Why pay for your legal research?
The open web is becoming almost as good as Nexis in searching for current news. Older news is still better served by a paid access database, since digitization is not uniform. The law seems to be following the same direction. The paid tools still have a distinct advantage in completeness and ease of use, and likely always will. The question is at what point does the cost differential make up for the functional differential: when the free web can provide 50 percent of the functionality? 75 percent? 90 percent? Or will less expensive tools that can provide most of the benefits at the fraction of the cost take hold?