I spent about £650 on my PC last year, and Cemu runs 100% with games like MK8 and Super Mario 3D World, others, like Bayonetta, not so much. Using games like Persona 5 on RPCS3 is just about playable, but there is a generous amount of stuttering. I would recommend a mid-to-high range i7 processor, a GTX 980 or above, and at least 8GB of RAM.