non-profit hosting?

I've got kind of a unique situation, so this may take a few moments to explain..

I've been hired by a non-profit orginization (gotta love the tax breaks) to design their website. The problem I'm having is that they are looking for VERY cheap or free hosting with the following capabilities:

1.) PHP/MYSQL (preferrably PHP4) and CGI access.
2.) ~100 email aliases (not needed really, but would be nice)
3.) 100 MB of space (give or take)
4.) around 5-6 GB transfer (they want a chat room).
5.) Unix hosting (just because Microsoft is evil)

That's really about it. They are willing to spend about $20 a month, but they'd really like it free and are willing to advertise the hosting provider, etc (just no forced banner ads like Hypermart, etc does)..

Does anyone know of any provider that's willing to host this non-profit site? They do have a tax id and all that fun stuff, so it'll be a tax break for the company who does host them for a reduced fee/free..

Thanks!