Help with path forward

Hi i currently own a rift S, and i am just wondering what the step forward would be, im mainly pcvr/sim and play games such as Beamng, assetto

My gtx 1080 wants to alr die but I won't let it. Im thinking about a 30 series like a 70 or a 80 I just want to know price, your opinions, and what would be the best step, My price point would be up to like 5-600 gbp, im fine with used i dont really care about condition.