If you're looking for free stuff I would start by youtube. There are tons of sound effects, some of them several hours clips. Download it, and then "export audio" in quicktime. Sound quality is sometimes quite good. For that kind of project you might just find exactly what you're looking for.
I think if the OP wants to handle the legal ramifications properly on his project then he can't depend on a YouTube video upload. Furthermore, you can't really trust a random website with downloadable sounds to be on the "up and up".
There are online services that, for a fee, provide sound effects in which the copyrights are controlled by the service. Many of these are of the "royalty free" variety...if you've paid the upfront fee then you owe no royalties for subsequent use. Some may require a credit in the film.