Those are all the legit (by legit, I mean time-tested) sources that I know of.
Other companies might make tests, but the ones you listed are the best-known for their accuracy.
I didn't use Barons, but I recall some people complaining that it had a lot of errors and the difficulty didn't match the real DAT in any way.
Kaplan is good for learning their stuff, they use TopScore Pro to measure how well you learned the stuff.