Wu_tian :
So is it a good idea to buy amd cpu and motherboard now?
No, Zen will be much more powerful, 40% more power per core. The current models aren't good for gaming really. They play some games well, but if you look at gaming holistically, they can't keep up with Intel.
Word is Zen is supposed to debut Q4 2016, so if you're intent on AMD, I would wait for that. IMO their current GPUs are not as good as Intel either, at least not at the high end. The problem with that, is AMD's high end Polaris won't be out until 2017.
That said, you seem to be only interested in lower price points, and we have yet to see what Zen chips will start at.