There are companies out there that offer 3D models at reasonable prices. For example, Dexsoft Games has a lot of very good stuff and their packages don't cost an arm and a leg. I've actually bought a couple of their material packages that I'm planning on using for testing purposes (and perhaps even in the game, I'm not sure yet).
You might point them at that resource (and there are a few others out there like that).
Having said that, you have to be careful. Not all models work with all engines (some engines require closed models, some have specific requirements about skeletons, and so forth). They ought to make sure the models they are looking at will work in the engine they are working with.
Now, for me personally, I have a little bit of skill (though certainly not professional level) with modelling, and I've gotten pretty good at navigating through Maya. So I intend to be building a few of my own models at first. Especially for the static (read: unskinned) stuff.
However, I probably don't have the skillset to do a fullly rigged and animated character, and may have to farm out some of that work.
Also, while I have a few skills with Photoshop, I haven't really got the artistic talent to do really good materials, so I may also be looking for people to do that as well (or I may buy some packs, probably a combination of both).
As to where I intend to find the people to do that work, we'll have to see when we get there. By that time I hope to have some sort of income from the engine itself, so perhaps I would be able to afford to hire out a bit of contract work. Who knows, heh. That's far enough into the future that I'm not going to worry over it at the moment.
"They laughed when I said I was going to be a comedian ... They're not laughing now." - Bob Monkhouse