I do a lot of presentations, and I am just now getting ready for two half-day workshops for the AIIP conference. Unlike most of my talks, at this one I'm paying for all of the expenses myself, so I decided that I didn't feel like paying the hotel $500 for the privilege of using their projector. I discovered Projector123.com, which will ship a projector to your hotel via FedEx the day before your presentation and provides a pre-paid FedEx label for returning it when you're done. For a fifth of what the hotel wanted to charge me, I've got a perfectly good projector for $100. Comes with instructions, a toll-free panic number, and it plays well with my Thinkpad.
Yeah, in most settings you still have to pay the hotel a usurious rate for a screen and a cart to put the projector on, but that's negotiable if you just ask.... I got mine for free since it was in conjunction with a conference, for example.