You might want to refer to this forum thread which says that Adobe has been able to take advantage of some of the newer Intel CPU chips with built in GPU's to achieve GPU acceleration. I seriously doubt that the GPU gain is anywhere near what an nVidia card can do but as a start-up system it would be worth a try.
The latest Pr CC (7.2) update touts improved OpenCL performance. Anyone has any clues, how much of an improvement it was?
(The key question of course remains, how much closer are AMD cards now to NVidia's performance-to-buck ratio?)