My understanding is that most professional animation houses tend to use proprietary software for most of their stuff, so they've got a team of programmers developing the tools on an ongoing basis. Also, that software is usually not for sale.

But, having said that, there are several really good 3D animation packages available. Lightwave, 3D Studio, Alias, SoftImage. The first in the list is the cheapest at about $800. SoftImage is a few thousand, I think. Some animation companies use this sort of high-end commercially-available software instead of developing their own. The kid's show "Jimmy Neutron," for example, is produced largely with Lightwave.

There's also a bunch of mid-range tools on the market. One of my favorites is trueSpace. (Co-incidentally, I just bought the upgrade for trueSpace a couple of days ago. Was considering Lightwave but I'm more comfortable with the tS interface.)

But there's at least one thing that most professional animators have in abundance that has thus far evaded me: talent. I've read interviews with a lot of top-notch animators and they often say that it doesn't matter what software one uses...if you have the talent, you'll be able to make any software sing.

*Sigh*
I'm thrilled when I can get it to hum a tune.