It depends on what options he wants.
3D Studio Max 7 is available as a Non-Commercial Student License for $480, but you would have to purchase it for your dad.
Other companies have similar deals for thier software.
currently the industry standard for CGI work is quickly becomming Softimage|XSI due to thier push for the movie industry to take it up as thier standard animation tool.
Softimage|XSI Foundation is under $1000, but not sure how much under. The problem is while, alot of the software will be at $500-$1000, your not going to find many solutions for under that without making some hard choices.
Wings3D is Free, you can then purchase Animation:Master for $120 for Animation needs, Blender 2.4.x is free which you can use to setup the scenes for the free YAFRAY (yet another free raytracer) which produces good results.
Editing up you could use Microsoft Movie Maker 2.1 (comes with Windows XP), or for better control Jasac do some good tools.
The problem with these solutions though, is they require alot more skill on the part of the artist.. and a better understanding of what goes into the development. Not to mention awekardly slow pipelines as you have to transfer everything.
So as I said, alot of tough decisions have to be made for budgets.
3D Studio Max, would be my best advice though for your price range.