Well, in my personal opinion - if I had $700 to get a DSLR, I would definitely go for a used one, so I could get an older pro-body, like a Canon 40D, Sony A700 or Nikon D200 or something of the sort. They won't have the newer features like video recording, but they are durable bodies that are much more functional in field.

However, that is only what I would do with $700 towards getting a DSLR. You might be wanting something for a completely different purpose. Do you want to have a lot of manual control over the camera or do you want to use mostly automatic functions?