Been reading up on this over the past couple of months. And no it is nothing to do with the crappy info you get on E-Bay.
You should see some of the stuff people are building, Hi-Def projectors 120" screens for around £300 mark, all depending on what sort of equipment you are buying really.
Got these images from another forum which specialises in home theater and projector building (they even sell their own pro projector for about £350 + shipping to UK) -
Lumenlab.com - Fiat Lux! - DIY Home Theater - HDTV - Video Projectors Gaming Projector 
Yellow Treasure 
And what im sure is heaven on earth, the full home theater designs 
That is correct, it is a ticket booth. This guy made a full fledged cinema.
Check this one out here -
HDTV and Home Theater Podcast - hdtvpodcast@mac.com
Thought it would be a topic many would be interested in. If anyone has done it please show images. Hope to have mines started by July this year.