While my Sketchup design used cheap linear rails and bearings, they still weren't all that cheap.
Here's a place that has materials that could be significantly less expensive: http://store.makerslide.com/
See also: http://www.kickstarter.com/projects/...bearing-system.
Also, to avoid lead screws, something along these lines might work: http://store.makerslide.com/index.ph...products_id=41
For aluminum extrusions, the following place has the best prices that I've found: http://us.misumi-ec.com/
Using these would allow someone to put together a system using very few tools.