$400? Add $100 and I would recommend Softimage|XSI foundation or the version of Lightwave they have on the Kurv Studio's website.
Hexagon and Silo? Well those are primarily modelling tools, I would assume he would want rendering/animation included, although both being top quality tools.
If you're going to spend $400, assuming you're new, I think you may like;
Milkshape or TrueSpace 5/6/GameSpace with Silo 2 or Hexagon 2, powerful modelling tools, with an animator (And a render with trueSpace.
My personal recommendation would be TrueSpace 6 with Silo, Silo for modelling TrueSpace for everything else, download the demo's and see what you like.