You are right. Bastion characters are made in 3d first with programs like 3ds Max, and then rendered all animation frames. If yoy want make 3d characters, you need to star from modeling. If you not have acces to complete modelling/animation/rendering expensive programs like 3ds max, Maya, Softimage... the tipical answer is Blender. But I suggest you to start from Silo, it is only for modeling, and it is very intuitive to learn, plus you have tutorials in the main page, and a good forum. It has 30 days trial demo, and the license is not too expensive (159$). As an alternative free modeling tool there is Wings3d, very good one too.
Wings 3d: wings3d.com
You have too, sites like thegnomonworkshop.com with many DVD to purchase with subjects like you are searching:
And many forum and social mnetwork like cgTalk or polycount.com
You can ask me too ;)