If money is not a problem, then I think you should not try to hit the perfect solution the first time. Trying to do that will make it harder to get started. I had to build a linear motion platform last spring. Since I had never done anything like that before I decided to just start buying stuff and testing it. I started with some small servos and brackets from Trossen Robotics - http://www.trossenrobotics.com/c/hobby-servos-for-robotics.a... and some Phidgets USB controllers from http://www.phidgets.com/

I started with the servos because it seemed cheaper and I could start without having to build a lot of stuff.

Then once I was happy with being able to control a two-axis setup with a little webcam on it using Python on a Linux box, I moved up to some 185oz-in steppers from Keling and some more Phidget stepper controllers. One of the big motors with a toothed belt can lift a full can of paint and hold it indefinitely.

I chose the Phidgets over Arduino because I didn't want to have to simultaneously learn a new toolchain while I was concentrating on the mechanical stuff. I figure I can always go to an Arduino or other controller if I need to shrink things down.

Having now worked with the steppers, I would second the idea of using DC motors with some kind of external feedback, maybe optical shaft encoders or something. Even with steppers, where you can count the number of steps and know where you are, you still really need to be able to run it into a limit switch in order to find some kind of a zero point.