It is easier to find free *.fbx files. You get the free converter from autodesk and
converter them to 2010 format and than you can import them to MED and save out as a *.mdl.
turbosquid.com have some free file. I will see if I can dig up some link real quick and provide links to the thing I posted here.
EDIT* A note about working with models - It can be some work to modify a model to work with 3dgs. It is hard to find models that are to say plug and play. You will need to spend a little time learning the tricks and tips for getting model ready for 3dgs. But this is good even if you are not going to be the project artist because many times you will need a understanding of how to incorporate outside produced models.
This site is great if you want to spend a little money. You get models you can use and good support.
http://www.dexsoft-games.com/ of course you could find this one on the forum already. For designing a project I get two or three paid models and use those. When the final phase of production comes then I save my pennies made fill a wish list. The great thing is once you have a model you can use it for designing many games till you have to finally replace it with a model that fits the project. ALWAYS back up your models... I've had to pay twice and I hate that...
The AU
SITE has free mdls, great for testing. Can't bet free..! I have many time used this
TEST_DUMMY MODEL.
Even if you are not making models, having a modeling program(not MED) to animate them with new animation sets is key and not to hard to learn. Plus if at the end of your project you want to replace a model with a custom one build for you, having even a bad example of the animate can help the artist create a really good models with less description and redo's
Teaming up with a artist is very helpful. I was thinking about fishing artist forums to see if I can get some students to post for practice or paid work here in this forum.