Okay apologies in advance if this is no good - or a completely dumb idea, but is it worth looking at other game creations sites for this. Ã‚Â I don't mean stealing their models - but for example TheGameCreators make a product called FPS Creator. Ã‚Â As part of that you can buy independent model packs essentially to use in the games you make.
But I can't see anything in the license to say you can't use them elsewhere - you are buying them for your own games, which are allowed to be commercial.
I'm not a modeller so I don't know whether the format they are in could be used or if the quality or polygon count etc. is what you need - but it might be worth a look?
They are not free - but not expensive either.
Here is an example zombie pack:
Here is an overview of all the packs (some are no good as they are walls and furniture and stuff like that:
I can only find copyright information relating to the games you make - not the packs themselves, but if you can make a commercial game with the models in them then I am thinking you could use them for any game perhaps:
Anyway like I said - maybe this is no use at all, just thought it might be worth a look.