I don't know if it is common, but from what I've seen, a lot of schools are willing to accept transfer students. The problem with transferring though is that you can only bring a designated number of credits with you to the new institution. Also, the new program might not view your previous courses as being equivalent to their own, so you might have to re-take some classes. Something like this happened last year with a student who transferred in during her second year, where she had already taken a course about the physiologic evaluation of the auditory system (ABR, ASSR, OAEs, etc) in her original program, but when she transferred to our school, the professor quizzed her about her knowledge, she failed, and had to retake the class.