I would advise waiting until you can afford the GPU. If you get a A10 7850 or 7870, you are paying for a decent iGPU in the chip. As soon as you add a discrete GPU of any power, you are 'throwing away' the money you paid for the now disabled GPU. In the long run, an Athlon X4 860K plus a GPU will be quire a bit cheaper.
Those games are quite CPU heavy and I would suggest that you look at an Intel i3. However, you have a very small budget. Plan B might be to buy a refurbished business desktop with decent specifications, and add a GPU to it. Could be both cheaper and better.