One of the local shops here has Specialized, and a whole wall of red and white Specialized test saddles that a person can sign out for a week or so and test. I personally don't get on with that brand and wish other manufacturers had the same setup, although I suppose it would take up a lot of space.
I do know that some shops have loaner saddles in the more expensive models. My husband test rode his favorite one that way before taking the plunge and buying one.