The April 2008 issue of Discover Magazine just arrived. There's an article called "Space Treks" ("seven ways to be a space tourist even if you're broke"), and it covers zero-G flight (which the reporter tried, $3500) and a range of pricier and some not-quite-yet available options (suborbital for $200K, ISS orbital for $30 million, moon orbit for $100 million). The usual space fan's dreams.
But at the low end, in the category "Virtually There," and coming in at an amazing "Cost: $0" is my favorite space flight simulator, Orbiter! Here's what it says:
Absent the money or time for any of the above, or if your ambitions go beyond the moon, there's only one option: going virtual. If you have a PC and an Internet connection, you can download - for free - the Orbiter spaceflight simulator, developed by Martin Schweiger, a physicist at University College London. Orbiter lets users pilot historical and fictional spacecraft around the solar system; options include flying a shuttle resupply mission to the space station and guiding a glider through the hazy skies of Venus.
That's all true, and with free add-ons, the range of things you can fly in Orbiter is quite amazing. The picture here shows the aforementioned Venusian skies with a fictional "space yacht" inspired by album art from the band Yes (more Yessongs pix and add-on info here). And to get started with the less exotic space station, moon, and Mars missions, you can also download my free Orbiter tutorial e-book Go Play In Space.