How much are these sprayers? What model did you use?
I'm pretty sure I'm going with an airless, but I like to keep my options open.
I painted a car with an airless sprayer once (ok, I was young and stupid, your point?

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They're ok for painting fences, patio furniture, maybe even a small house, but unless there have been some major advances in airless technology in the last 19 years (and there probably has) don't expect an incredible finish. They typically can only cover small areas at a time, are noisy and are pretty tempermental with paint viscosity (if the paint is too thick, it can actually damage them).
Likewise, if you aren't comfortable with a regular air sprayer, you could get poor results with that as well. Don't even think about spraycans, unless you are after the grafitti look.
On the other hand, a high quality roller and some good paint will probably come out better than you think. Just don't skimp on the roller if you go that route! Nothing screws up a paint job worse than roller fuzz all over your project (except maybe cat footprints

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Ok, enough preaching. Here's a place I just found (never did business with them)
http://www.gleempaint.com/powersprayer.htmlThey start at (reconditioned) $45.00
RandyT