The idea is that one could send back video from a lunar rover for entertainment purposes, for example display in a theme park. The price would appear to be plausible (compared with other theme park attractions). The company which has attracted most attention is LunaCorp (Potomac Institute, page C-15; LunaCorp home page), but these sources show few concrete accomplishments.
Forever Bound is a concept to launch cell samples of people on a solar escape trajectory. See "Forever Bound Offers Unique Space Entertainment," SpaceViews Update, 15 May 1996. Not clear how real this is; if there is an economic analysis behind it, it isn't in that article.
The projects to send names/signatures along with space probes are also examples:
The Kennedy Space Center Visitors Center (Florida, USA) and Space Center Houston (Houston, Texas, USA) are both large operations with IMAX theaters and the works. Both are, at least to some extent, independent of NASA, although I don't know just how far that goes. For example, I don't know how NASA would react if they wanted to make a deal with a non-NASA entity such as LunaCorp or one or more Russian space entities. For more, see my Kennedy page with more numbers and analysis, or the official Houston page.
There is an amusement park in Kitakyushu, Japan, called Space World with a full size shuttle and external tank (models, I presume) and other attractions. There is a Japanese-language pages concerning it here; according to that page attendance ranged from 1.8 million people in 1990 to 2.1 million people in 1995. The page also has data on things like gender, age, time spent per visit, &c, but you'll need to know a little Japanese to read it.
The National Air and Space Museum in Washington, DC gets 10 million visitors a year (source: Hemispheres (United Airlines inflight magazine), March 1999, page 32). Since they don't charge admission, it is a bit hard to compare with an attraction which does.
The Kansas Cosmosphere and Space Center (Hutchinson, Kansas, USA) gets 300,000 visitors per year, according to "Spaceport Kansas: A Visit to the Kansas Cosmosphere and Space Center", SpaceViews, Aug 1996.
Gorky Park in Moscow, Russia just spent $3 million on their new Buran ride, according to "Liftoff, $35", The Washington Post, Tuesday, 16 Jul 1996; Page A11.
Much of what these parks do has only an indirect connection to spaceflight, but the parks do tie in to spaceflight and at least in principle could fund it.