Videomaker – Learn video production and editing, camera reviews › Forums › Cameras and Camcorders › Consumer Camcorders › Affordable Camera for Documentary › A lot of good suggestions
A lot of good suggestions here so I'm going to add my .02 worth.
If you're looking to purchase a camera or two, don't overlook eBay. I've purchased four used cameras over the last few years there and had great success and saved a bunch of coin. Most recent purchase: a Canon 5D MKII – for $1100! it has 185,000 shutter activations but I only wanted it for the video. Canon also has a service plan for about $100 that checks out the camera thoroughly. I know of two photogs who routinely send their cameras in for annual checkups.
I purchased two Panasonic AG-HMC150 cameras over a period of several months and in each case, paid far less than the going rate. Many videographers are selling their older camcorders in favor of DSLRs which typically cost a lot more, without a lens.
The trick to using eBay (works for me anyway) is to figure out what you want then search for it. Find some sellers who have the item, and put them on your watch list. See what they end up selling for. Check the seller's reputation, and if he has a 98% or more positive feedback, toss in a bid. Some people hate eBay but I've had a great experience finding decent used equipment at fair prices.
Another route is rentals. Google up camcorder rentals and see who will ship to you. Many online rental houses will do that. If you end up owning a DSLR and want a cinema lens, there's lots of rental houses that will have what you need. Cinema lenses can easily cost two and three times the price of the camera. Many documentarians rent equipment because there can be substantial savings over ownership.