I just bought a canon rebel that was used and pretty cheap compared to its original price at a national camera exchange story in minneapolis

they have a website but I don't think you can order any off of it,
but you can check out cameras and their availability at stores

http://www.natcam.com/Default.asp?USID={66CA8474-8DEE-4491-BDED-0055496C1EFE}
References :

Yes, check out craigslist, ebay, B&H, adorama. All of these are good places to get a used SLR or DSLR.
References :

Craigslist and eBay are two other options.

I've bought camera gear off eBay and have never been dissatisfied. Of course, I deal with sellers I trust (one I use is Shutterblade, a dealer in all sorts of used photo gear). In addition, I have also bought from private individuals, also on eBay as well as privately, and have also had positive experiences.

I've not had any experience buying off Craigslist, so I'll simply advise you to be careful from whomever you buy.
References :

A digital SLR? Stick with Canon or Nikon, they offer the best and most versatile stuff. KEH is a great site for used equipment, but also try ebay. I believe B&H and Adorama also have used sections as well. I'm not selling you mine
References :
http://www.bhphotovideo.com/c/shop/2891/Digital_Cameras_Accessories_Digital_Cameras.html
http://www.adorama.com/catalog.tpl?op=category&cat1=Used
http://www.keh.com/onlinestore/home.aspx
http://www.keh.com/onlinestore/home.aspx

Check amazon.com there always have good deals
http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2FDigital-SLRs-Cameras-Photo%2Fb%3Fie%3DUTF8%26node%3D3017941%26ref%255F%3Dsv%255Fp%255F2&tag=computer0bd-20&linkCode=ur2&camp=1789&creative=390957
References :