some people on these forums give away free 3D models that aren't likely to be animated, there should be an animated model on the DBP disc.
Most 3D models on the internet cost you money. you can animate models in DBP depending on how the model is made (Or anyone correct me if I was wrong) So I would say is buy or download a free 3D modelling program, if you follow tutorials you will model good in little time and animate them. (All of the free 3D tools I know are useless for animation)
For a 3D modelling program, here is a list and a comment for each one. (I'd use google to look for websites)
Milkshape 3D-£20- Most popular for people with little money and I have seen many people use this, provide a bunch of free 3D tools, good for animation
Anim8or- Free- Popular, you can get really good stuff out of this, but the problem is its not good for animations to import into your games.
Wings 3D- Free- In my opinion its a lot like anim8or but with a more Cinema 4D GUI (Graphical User Interface)
3D Canvas Plus/Pro -£20-40 - You don't want the free version considering you won't be able to use the models. You will need to use tutorials for this prog (there is a section dedicated to the program on this forum) Good for animation.
GameSpace - £100- this is going a bit crazy with your money but it provides awesome power for model making with various tools and supports a great tool for animation.
TrueSpace 5.2-6.6 - £200-350- This is a lot like GameSpace, but has more tools, and allows you to render movies to file (so does anim8or as I forgot to mention) Unfortunately tutorials for this program cost money too, but there are free tutorials around, I use version 5.2 and the dark matter models were made using this tool.
Cinema 4D R9, £500, £1300, £2200 - I doubt you will buy this one, but it provides ultimate power, but is not the best nor the most expensive. See the Polar Express for results of its produce.
Soft Image|XSI- not sure about price - Better than Cinema 4D (well thats what i heard) for examples of Showcase see Metal Gear Solid: Snake eater.
Lightwave- about £900, very powerful renderer, offers similar tools to Cinema 4D, TrueSpace and XSI
3DS Max- £2000, A big price for a big program, very powerful, good stuff, offer all the games tools you'll ever need. See Prince of Persia: Warrior within.
Maya £2000/£5000, the bitch of a price but well worth the package, not many game making users use this (because 3DS max catches them) mainly used for 3D CGI, see Robots, Shrek, Toy Story, The Incredibles etc...
or you could just short cut it and use other peoples models