iMacs for non-profit

I am part of the Womens Caucus for Arts (NH) and we are planning an art incubator in a small town in NH. I've been arguing that we need to use Macs and have a .Mac account because of the graphic interface and ease of use for newbies (we have ALOT of newbies!) (Also, I'm a Mac addict) The nay-sayers say they are too expensive and good deals can be found for PCs. Are there any places to buy iMacs for non-profit organizations (at good prices!) and software too. I've been searching all over the web, but I've only found sources for education and federal gov. Any tips? Thanks!