Most 3D rendering software is expensive. I have a copy of Houdini (used to make Toy Story) which retails at $15,000 (of course I didnt pay full price for it). However, there is a program called Maya. They have a free version of the program online, its not a full version but I im pretty sure you will be able to work it for what you want to do.
Maya is the Best but it is very Tuff i mean one must take a Course for to learn it
i do have it installed in my system but i need somone to teach it to me.