Houdini was a niche high end (back when there was such a thing) 3d app that used to sell for tens of thousands of dollars. It looks like Houdini Master is now about 8 grand. No idea what kind of functionality it offers.
Houdini is used a lot even by smaller studios. One of my 3d teachers working on fight club used only Houdini for the entire sculpture/giant ball crashing through stuff scene, apparently. And that team only consisted of 2-3 guys
Lupus, its mainly great for big ass projects with lots of people. For smaller one man projects, I prefer other 3d programs. But they have updated the UI. Maybe its better now. 3dbuzz is a great place for houdini tuts btw.