The gpu in PS4 was a cut-down radeon 7870 card, that card launched at $350 in march 2012. I think the PS5 price will be $500 with this gpu amd showed at computex. We not sure what the gpu will cost, but probably between $400-$500.
I still have very severe doubts about the 5700 costing that much. The whole point of Navi's highest and 2nd highest tier GPU's was to bring Vega 64 and Vega 56 tier performance to the mid-range consumer with greater power efficiency. You can already buy a Vega 64 for $400 now if you bargain hunt. Navi is the successor to Polaris, AMD's last mid-range GPU line, and the most expensive Polaris GPU on release, the RX 480, was $250. I don't know if they will be able to hit $250 with this 5700, but I will be surprised if it costs more than $300, prices over about $300 just aren't appealing to the mid-range consumers that Navi is targeted at.