Maya has features that are well worth the price for a company looking to produce professional computer animation. With Maya (and other high end animation programs) your animating a character with a skeletal system, muscles and skin, not just a model with bendy parts.

Professional productions with Maya generally take a full team. You need modellers, texturers, lighting technicians, animators, and some place even hire "Render Watchers." Poser's strengh is that it takes all the basics and makes it easy for one person to handle it all. Poser's biggest asset is all the ready-made material for it, through DAZ, the other store, the freebies, and just the stuff that comes with the package. Buy Maya and you may need to spend anywhere from a months to a year modelling a character to animate with it.

Maya costs around 10k. It's sold by Alias|Wavefront. Generally you are not only buying the software itself, but a complete support package.

Walking with Dinosaurs was animated in Softimage (Maya's most direct competitor) and composited onto live-action plates with 5 compositers using Quantel's Henry and another 5 using Discreet Inferno.