LCD projectors are neat little devices.  You can project computer output on a large screen for either many people to see at once, or just for your own personal pleasure in gunning down life-sized critters.  However, they're also quite expensive: a bare miniumum projector will easily run you $1000.  And the replacement bulbs can easily cost $250.

  An option is to buy technology that's a few years old.  The predecessor to today's LCD projectors is the LCD Projection Panel, which was essentially an LCD monitor without a backlight that was placed on top of an overhead projector (OHP, to save my typing skills).  In their day (mid-late 90's), these little buggers were even more expensive than today's LCD Projectors:  a base model was about $3000, and an XGA model could set you back $14,000.  I kid you not.

  Now that the hardware industry has moved on to bigger and better things, no salesman worth his spats would be caught dead making a presentation on such Flintstonian hardware as a big bulky OHP and LCD panel.  Enter Ebay:  you can pick up a decent basic panel for less than $100.  Decent XGA models usually go for about $300.  If you want to show video, you'll either have to find a panel with S-Video or Composite inputs, or spring for a line doubler to convert the video signal to VGA.

  OHPs are a dime a dozen.  I have bought 3 for about $20/ea.  But here's a couple of problems lurking:

(1)  in order to have a decent projected image,  it should be at least 500 lumens (of course, 'decent' is a relative term.  Here, it means "easily visible in a darkened room").  Most low-level OHPs put out about 2500 lumens.  Almost all LCD projection panels will only pass about 10-15% of the supplied light, so that boots your 2500 lumens down to 250 lumens at the screen:  too dark for most viewing.  

(2) right at the point where an OHP begins to put out enough light to make a good projected LCD image (4000-5000 lumens), you run into a limitation of the halogen bulbs.  The next step is to go to a Metal-Halide driven OHP.

(3) the MH OHPs are quite powerful (575W, puts out 7000-8000 lumens), but they're rare (=expensive, usually about $200), and the replacement bulbs are costly (usually about $100).

  So, the obvious solution is to figure out a way to upgrade a standard (=cheap) OHP with a reasonably-priced MH bulb.