Well... The next gen GPUs from AMD got announced which is the RX 480 and it's 5+ TF. Most likely around 5.5TF according to "leaks" and its priced at $200 which is coming out pretty soon so... Its certainly not gonna be that expensive.
I say around $500sh since its coming out next year
PC Specs: CPU: 7800X3D || GPU: Strix 4090 || RAM: 32GB DDR5 6000 || Main SSD: WD 2TB SN850