I personally don't have the time, but you will have a better chance convincing people if you tell us about the project, what the timeline is, and what the people who help will get out of it. Showing your current progress would really help as well. You see, from our perspective, a stranger has just walked into the room and asked us if we would do work for nothing. If you can get people interested, excited, and feel like they are getting something worthwhile in return (tangible or intangible) then people will be more likely to help out.
If you can't find help, you can try to find what you need at BlendSwap
. Just be careful to respect whichever license the models are under before using them.
And to be clear, I might not be able to help make models, but I can answer any questions, give critiques, and help point you in the right direction if you need it.