It would be hard to out perform the Intel I3, I5 and I7 series. They are reasonably priced as they have been out for a while. I have seen I3 and I5 Intel units ( laptops ) for $ 100-150 dollars.
I have a Dell 17 inch laptop that was purchased new for about $ 500 dollars about 4-5 years ago. It came equipped with a quad core A8-7410 AMD CPU with an integrated video section and a 2 Tera byte hard drive and 16gb of Ram. It performs well and has a TDP of 15. It runs windows 10 which I don't like. Out of curiosity, I loaded SH3 with GWX and it performs well with enough frames per second to pass muster.
I think you will do well with this setup. I was given an " all in one " Dell 24 inch or so computer. It also has a touch screen. I replaced the hard drive in it. All in one computers use a laptop motherboard and this model had the A8-7410 AMD CPU. The computer has a 500gb SSD loaded with Windows 7 and is very fast. Silent Hunter works well on it too.
Just some thoughts I wanted to share. Good luck, John.