Jakob Nielsen found that only 76% of people who wanted to do a search could actually do so. See http://www.useit.com/alertbox/designer-user-differences.html -- it's quite long so search for "Getting to Google is hard"
My personal non-scientific experience is that users who are so internet-clueless are also e-commerce-phobic... They won't put their credit card and personal data "into the intarweb". So, the value to a retailer of this group of folks that can't master ANY search engine is probably much less than the cost of developing and promoting these sites based on such great domain names.
I think the Plenty of Fish model (lots of traffic, high priced sponsorship ads and affiliate links to more targeted or efficient sites) is a better bet for high value domain names, given that characteristic that you pointed out about the people unable to find a search engine. They might not know what they're doing, but you can be darn sure they click on ads!